.   .    LIBRARY    .    . 

Connecticut 
Agricultural  College. 

VOL iA.X5..0 

CLASS   NO. Q..J).    Q 

r  - !)  I 

COST yj?  VjM^ 

DATE J.JJL:, 1.. 19  /-^. 


Digitized  by  tine  Internet  Archive 

in  2009  witii  funding  from 

Boston  Library  Consortium  IVIember  Libraries 


http://www.archive.org/details/mesozoiccenozoicOOclar 


DEPARTMENT  OF   THE   INTERIOR 


MONOGRAPHvS 


OF   THE 


United  States  Geological  Survey 


VOLUME    LIV 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 
1915 


UNITED   STATES   GEOLOGICAL   SURVEY 

GEORGE   OTIS  SMITH,   Director 


THE 


MESOzoic  AND  cenozok;  echinodermata 

OF  THE  UNITED  STATES 


BY 

WILLIAM  BULLOCK  CLARK 

AND 

MAYVILLE  W.  TWITCHELL 


WASHINGTON 

GOVERNMENT    PRINTING    OFFICE 
1915 


li  X  5  0 


CONTENTS. 

Page. 
7 
Preface ; 

Part  I. — The  Mesozoic  Echinodermata,  by  William  Bullock  Clark 9 

Introduction 

Geologic  and  geographic  range 9 

Bibliography 

Triassic  Echinodermata 21 

Crinoidea ^'■ 

Pentacrinidis -■'■ 

Encrinidae ■ ^^ 

Stelleroidea - ^^ 

Amphiuridae ^"J 

Echinoidea ^^ 

Cidaridse — ^ 

Jurassic  Echinodermata ^ -^ 

Crinoidea ^^ 

Pentacrinidse ^° 

Stelleroidea -  ^^ 

Asteriidas "° 

OpMolepidid;<? "" 

Echinoidea ^^ 

Cidarida; 3° 

Hemicidaridse ^'■ 

Diadematidse '^■' 

Pedinidse ^^ 

Pygasterid» ^^ 

Cassidulidre ""^ 

Cretaceous  Echinodermata ■^'^ 

Crinoidea '^^ 

Pentacrinidse "'■' 

UintacrinidiP ^^ 

Marsupitidii? ^" 

Bourgueticrinida' ■^" 

Stelleroidea *'- 

Astropectinida=. *^ 

Pentagonasteridse ' '^'- 

Atheneidae ■*-■ 

Pentacerotidaj ^^ 

Ophiolepidid^ '*■' 

Echinoidea ^^ 

Cidaridaj ■*■* 

SaleniidfB ■ "*" 

Hemicidarida^ ^^ 

Orthopsida> ^* 

Diadematidaj ™ 

Diplopodiidae r °° 

Cyphosomatidae ^° 

Triplechinida; ^^ 

Pygasteridae "" 

Cly  peastridio " ' 

Echinoneidae " ' 

Nucleolitidai ^^ 

Cassidulidae '  ^ 

Echinocorythida? °'- 

Spatangidae "" 

3 


4  '  CONTENTS. 

Page. 

Part  II. — The  Cenozoic  Echinodermata,  by  William.  Bullock  Clark  and  Matville  W.  Twitchell...  101 

Introduction 101 

Geologic  and  geographic  range 101 

Bibliography 105 

Eocene  Echinodermata 112 

Crinoidea , 112 

Antedonidfe 112 

Stelleroidea 112 

Asteriidse 112 

Echinoidea 113 

Cidaridae 113 

Arbaciidfe 117 

Cyphosomatidw 118 

Triplecliinidiie 118 

Fibulai-iidiie 119 

Laganidee 122 

Scutellid^e 124 

Clypeastrida? 136 

Cassidulidae 140 

Spatangida? 150 

Oligocene  Echinodermata 157 

■  Echinoidea 157 

Cidaridae 157 

Arbaciidse 158 

Cypho.somatidaf 159 

Triplechinid'e 159 

Fibulariida? 160 

Laganidse 160 

Nucleolitidse > 165 

Cassidulidae 170 

Spatangida? 174 

SynaptidK 177 

Miocene  Echinodermata 178 

Stelleroidea 178 

Asteriidse 178 

Ophiodermatida? 178 

Amphiuridae 178 

Echinoidea 179 

Cidarida; 179 

Arbaciidae 180 

Triplechinidae 181 

Fibulariidre 182 

Scutellidae 183 

Clypeastridfe 209 

Cassidulidae 211 

Spatangidae 212 

Pliocene  Echinodermata 216 

Echinoidea 21 6 

Strongylocentrotidae 216 

Scuteiiidfe 216 

Clypeastridae 218 

Cassidulidae 220 

Spatangidfe 221 

Pleistocene  Echinodermata 222 

Stelleroidea 222 

Asteriidse 222 

Echinoidea 222 

Triplechinid* - 222 

Strongylocentrotidae 223 

ScutelUda; 223 

Spatangidae 227 

Index ---  337 


ILLUSTRATIONS. 


Page. 

Plates  I-CVII.  Mesozoic  and  Cenozoic  Echinodermata 228-336 

CVIII.  A,  Astrodapsis  tumidus  Kemond  in  matrix,  Santa  Margarita  formation  (upper  Miocene), 
Nacimiento  River,  San  Luis  Obispo  County,  Cal.;  B,  Dendraster  gibbsii  (Remond)  in  upper 
Miocene  (?)  beds,  K.  W.  Jones  rancli.  Kings  County,  20  miles  southeast  of  Coalinga,  Cal 336 

5 


PREFACE. 


The  study  of  the  Mesozoic  and  Cenozoic  Echinodermata  of  the  United  States  was  commenced 
by  the  senior  author  of  this  paper  under  the  ausjjices  of  the  United  States  Geological  Survey  in 
the  autumn  of  1890  and  has  been  continued  with  frequent  interruptions  to  the  present  time. 
During  recent  years  he  has  had  associated  with  liim,  in  the  study  of  the  Cenozoic  forms,  Dr.  M.  W. 
Twitchell,  formerly  a  graduate  student  at  Johns  Hopkins  University  and  now  assistant  State 
geologist  of  New  Jersey,  who  has  confined  his  investigations  cliiefly  to  the  Clypeastrina  and 
Asternata.  Several  papers  containing  results  of  tliis  study  have  been  prepared  by  the  senior 
author,  the  most  important  being  one  entitled  "The  Mesozoic  Echinodermata  of  the  United 
States,"  which  was  published  in  1893  as  Bulletin  97  of  the  United  States  Geological  Survey. 
Other  contributions  have  appeared  from  time  to  time  as  the  work  has  proceeded. 

Few  American  paleontologists  have  investigated  the  Echinodermata,  and  no  one  of  them  has 
hitherto  attempted  a  general  systematic  study  of  the  Mesozoic  and  Cenozoic  representatives  of 
this  group.  Much  confusion  has  therefore  existed  as  to  the  specific  and  generic  relations  of  many 
of  the  forms,  and  their  geologic  distribution  has  been  in  much  doubt.  Some  of  the  forms  are 
very  numerous,  and  because  of  their  wide  geographic  and  i-estricted  geologic  range  are  valuable 
in  determining  questions  of  correlation.  The  revision  presented  in  this  contribution  should 
therefore  be  of  some  value  in  stratigrapliic  geology. 

No  attempt  has  been  made  by  the  authors  to  modify  mateiiallj'  the  recent  classifications  of 
the  Echinodermata,  which  are  based  on  exhaustive  study  of  far  greater  and  much  more  repre- 
sentative materials  than  those  afforded  by  American  deposits.  The  authors  have  followed  very 
closely  in  theh  major  classification  that  of  F.  A.  Bather  in  "The  Echinodermata,"  in  Lancaster's 
"Treatise  on  zoology,"  and  in  their  generic  usage  that  of  P.  M.  Duncan  in  his  "Eevision  of  the 
genera  and  great  groups  of  the  Echinoidea." 

Many  courtesies  have  been  extended  to  the  writers  in  connection  ^ith  this  study,  and  all  the 
large  collections  of  the  country  have  been  put  at  their  disposal.  Among  the  more  extensive 
collections  used  have  been  those  of  the  United  States  Geological  Sui-vey,  United  States  National 
Museum,  Academy  of  Natural  Sciences  of  Pliiladelphia,  American  Museum  of  Natural  His- 
tory, Wagner  Free  Institute  of  Science,  Museum  of  Comparative  Zoology  of  Harvard  College, 
Peabody  Museum  of  Yale  University,  Cincinnati  Society  of  Natural  History,  Walker  Museum, 
Carnegie  Museum,  Field  Museum,  Boston  Society  of  Natural  History,  Johns  Hopkins  Uni- 
versity, Wilhams  College,  University  of  CaHfornia,  Leiand  Stanford  Junior  University,  Amherst 
College,  Maryland  Geological  Survey,  New  Jersey  Geological  Survey,  Texas  Geological  Survey, 
Alabama  Geological  Survey,  P.  de  Loriol,  and  Robert  T.  Jackson. 

The  authors  desire  particularly  to  express  then-  appreciation  for  valuable  personal  aid 
rendered  by  numerous  paleontologists,  among  whom  should  be  especially  mentioned  T.  W. 
Stanton,  of  the  United  States  Geological  Survey;  J.  W.  Gregory,  of  the  University  of  Glasgow; 
W.  H.  Dall,  of  the  United  States  National  Museum;  Robert  T.  Hill,  formerly  of  the  United 
States  Geological  Survey;  Frank  Springer,  of  the  United  States  National  Museum;  John  C. 
Merriam,  of  the  University  of  CaUfornia;  and  Ralph  Arnold,  until  lately  of  the  United  States 
Geological  Survey. 

Most  of  the  illustrations  have  been  made  under  the  direction  of  J.  L.  Ridgway,  of  the  United 
States  Geological  Survey.  Many  of  the  earlier  drawings  from  Bulletin  97  (The  Mesozoic  Echino- 
dermata of  the  United  States),  made  by  C.  R.  Keyes  and  H.  C.  Hunter,  are  incorporated  in 
this  volume. 


THE  MESOZOIC  AND  CENOZOIC  ECHINODERMATA 
OF  THE  UNITED  STATES. 


By  William  Bullock  Clark  and  Mayville  W.  Twitchell. 


PART  I.— THE  MESOZOIC  ECHINODERMATA. 


By  William  Bullock  Clark. 


INTRODUCTION. 

GEOLOGIC   AND    GEOGRAPHIC   RANGE. 

The  remains  of  Echinodermata  are  found  in  Mesozoic  deposits  at  nearly  all  horizons  and 
at  ^videly  separated  localities  but  are  much  more  numerous  and  characteristic  in  Cretaceous 
than  in  Triassic  and  Jurassic  strata.  In  several  of  the  Cretaceous  fonnations  they  are  among 
the  most  valuable  diagnostic  fossils,  and  at  a  few  localities  they  occur  in  vast  numbers. 

Comparatively  few  Triassic  forms  have  been  found.  The  most  common  are  crinoid  stems 
representing  the  genera  Isocrinus  and  Encrinus,  the  fonner  appearing  in  the  Lower  Triassic  of 
Idaho,  the  Middle  Triassic  of  Nevada,  and  the  Upper  Triassic  of  California,  and  the  latter  being 
confined  to  the  Upper  Triassic  of  California.  The  echinoids  are  represented  by  two  species  of 
Cidaris,  which  are  confined  to  the  Upper  Triassic  of  California.  In  addition  to  these  a  few 
indistinct  casts,  among  them  a  small,  poorly  preserved  starfish,  which  has  been  questionably 
assigned  to  the  genus  Aspidura,  have  been  found  in  the  Lower  Triassic  of  Idaho. 

The  Jurassic  echinoderms  are  somewhat  more  numerous  and  varied,  although  they  form  no 
considerable  proportion  of  the  known  American  fossil  Echinodermata.  The  most  common 
forms  belong  to  the  genus  Pentacrinus,  column  joints  having  been  found  in  Nebraska,  South 
Dakota,  Wj^oming,  Colorado,  Idaho,  LTtah,  and  California.  The  asteroids  are  represented  by 
both  the  OphiuridiB  and  the  Stelleridfe,  specimens  having  been  found  in  Wyoming,  South 
Dakota,  and  Utah.  The  echinoids  are  much  more  fully  represented  than  in  the  Triassic.  Sev- 
eral genera  have  been  recognized,  among  them  Cidaris,  Hemicidaris,  Pseudodiadema,  Stom- 
echinus,  Holectypus,  and  Pygurus.  Most  of  the  specimens  are  poorly  preserved  and  are  in  few 
places  numerous.  The  first  four  genera  occur  only  in  California,  being  found  in  both  the  Lower 
and  Middle  Jurassic.  One  species  of  Holectypus  occurs  in  Texas  and  another  in  Montana. 
Pygurus  has  been  found  only  in  Texas. 

The  Cretaceous  echinoderms  are  very  numerous  in  certain  areas.  A  great  variety  of  types 
is  represented  and  much  of  the  material  is  splendidly  preserved.  Many  of  the  species  are  nar- 
rowly limited  in  geologic  range  and  are  therefore  important  as  type  fossils. 

The  crinoids  are  represented  by  Uintacrinus,  Marsupites,  Pentacrinus,  and  Rliizocrinus, 
the  first  named  having  afforded  a  great  number  of  remarkable  specimens  in  the  Niobrara  chalk 
of  Kansas.  Springer  has  made  this  material  the  subject  of  an  elaborate  monograph,  and  most 
of  the  great  museums  of  the  world  contain  beautiful  specunens  from  the  now  famous  locality 
in  Kansas. 


10  MESOZOIC    AND    CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

The  stelleroids  contain  representatives  of  both  the  Ophiuroidea  and  the  Asteroidea,  the 
genera  Ophioglypha,  Astropecten,  Goniaster,  Pentagonaster,  and  Pentaceros  being  found.  The 
material  comes  from  widely  separated  areas  in  New  Jersey,  Texas,  and  Wyoming. 

The  echinoids  are  very  numerous,  both  the  regular  and  irregular  types  being  well  repre- 
sented. Both  the  Lower  and  Upper  Cretaceous  deposits  of  Texas  contain  many  species  and  vast 
numbers  of  individuals  at  several  horizons;  and  the  Upper  Cretaceous  of  the  Atlantic  and  eastern 
Gulf  coasts,  particularly  in  New  Jersey,  North  Carolina,  Alabama,  and  Mississippi,  although 
fully  characterized  by  its  echinoid  fauna,  affords  many  forms.  The  western  interior  and 
Pacific  coast  Cretaceous  contains  a  much  smaller  representation  of  echinoid  types. 

Among  the  Lower  Cretaceous  genera  represented,  more  particularly  in  Texas,  are:  Cidaris, 
Salenia,  Hypodiadema,  Goniopygus,  Pseudodiadema,  Diplopodia,  Cyphosoma,  Holectypus, 
Pja-ina,  Enallaster,  and  Hemiaster.  Outside  of  Texas  very  few  Lower  Cretaceous  echinoids 
have  been  recognized.     The  Horsetown  formation  of  California  contains  a  few  forms. 

The  Upper  Cretaceous  of  Texas  contains  a  large  echinoid  fauna  and  some  of  the  genera 
possess  many  species.  They  are:  Cidaris,  Leiocidaris,  Leptarbacia,  Orthopsis,  Heterodiadema, 
Cottaldia,  Diplopodia,  Cyphosoma,  Micropsis,  Holectypus,  Echinobrissus,  Cassidulus,  Anan- 
chytes,  Cardiaster,  Holaster,  and  Plemiaster. 

The  LTpper  Cretaceous  of  the  Atlantic  and  Gulf  coasts  has  afforded  representatives  of  the 
following  genera:  Cidaris,  Salenia,  Pseudodiadema,  Coptosoma,  Psammechinus,  Echinobrissus, 
Trematopygus,  Botriopygus,  Cassidulus  (many  species  of  which  have  been  recognized),  Catopy- 
gus,  Echi]ianthus,  Ananchytes,  Cardiaster,  Hemiaster,  and  Linthia.  Much  the  larger  number 
of  Atlantic  coast  forms  have  been  found  in  the  New  Jersey  Cretaceous,  especially  in  the  Vincen- 
town  sand  of  the  Rancocas  group,  which  is  regarded  as  probably  of  Danian  age.  The  western 
interior  and  Pacific  coast  areas  contain  few  representatives  of  the  echinoids,  most  of  the  species 
belonging  to  the  genus  Hemiaster. 

The  absence  of  species  identical  with  those  of  other  continents  and  particularly  of  Europe 
renders  impossible  a  detailed  correlation  of  American  and  foreign  horizons  on  the  basis  of  their 
echinoderm  faunas.  However,  genera  represented  in  the  main  divisions  of  the  Mesozoic  in 
ii.merica  are  with  scarcely  an  exception  similar  to  those  typical  of  the  same  divisions  elsewhere. 

The  accompanying  tables  show  the  stratigraphic  positions  of  the  more  important  American 
Mesozoic  formations,  the  geologic  distribution  of  the  Mesozoic  Echinodermata  of  the  United 
States,  and  the  stratigraphic  distribution  ot  the  Cretaceous  Echinodermata  of  Texas. 


INTKODUCTION. 


11 


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12 


MESOZOIC    AND    CENOZOIC    ECHINODERMATA    OF   THE   UNITED    STATES. 

Geologic  distribution  of  the  Mesozoic  Eckijiodermata  of  the  United  States. 


Crinoidea: 

Dicyclica — 

Inadunata — 

Dendrocrinoidea — 
Pentacrinidae— 

Isocriniis  smithi  Clark 

Isocrinus  californicus  Clark 

Isocrinus  sp 

Isocrinus  knighti  Sprinjier 

Pentacrinus  asteriscus  Meek  &  Hayden  . 

Pentacrinus  whitei  Clark 

Pentacrinus  shastensis  Clark 

Pentacrinus  tehamaensis  Clark 

Pentacrinus  bryani  Gabb 

Encrinidfe — 

Encrinus  hyatti  Clark 

Uintacrinldfe — 

Uintacrinus  socialis  Orinnell 

Marsupitldip — 

Marsupites  americanus  Springer 

Flexibilia — 
Pinnata — 

BourguetiicrinidEe— 

Rbizocrinus  alabamensis  de  Loriol 

Rhizocrinus  cylindricus  Weller 

Stelleroidea: 
Asteroidea — 

Phanerozonia — 

Astro  pec  tinince — 

Astropecten  (?)  montanus  Douglas 

Pentagonasterid:T? — 

Pentagonaster  brow-ni  Weller 

Atheneidte— 

Goniaster  maramillata  Gabb 

Pentaoerotido' — 

Penta?eros  asperulus  Clark 

Cryptozonia — 

AstcriidiP— 

Asterias  (?)  dubium  Whitfield 

Ophiuroidea — 
Zygophiurn? — 

Opbiolepidida? — 

Ophioglypha  utahensis  Clark 

Ophioglvpba  texana  Clark 

Ophioglypha  bridgerensis  (Meek) 

Amphiurida? — 

Aspidura  (?)  idahoensis  Clark 

Ecbinoidea: 

Regularia  endobranehiata— 
Cidaroidea — 

Cidarida?— 

Cidaris  shastensis  Clark 

Cidaris  dilleri  Clark 

Cidaris  californicus  Clark 

Cidaris  taylorensis  Clark 

Cidaris  plixmasensis  Clark 

Cidaris  tehamaensis  Clark 

Cidaris  texanus  Clark  . . . : 

Cidaris  walcotti  Clark 

Cidaris  splendens  Morton 

(■?)  Cidaris  dixiensis  Cragin 

Cidaris  nahalakensis  de  Loriol 

Leiocidaris  hemigranosus  (Shumard) . . . 
Regularia  ectobranchiata — 
Diademoidea — 
Calvcina— 

Saleniidre— 

Salenia  texana  Credner 

Salenia  tumidula  Clark 

Salenia  bellula  Clark 

Arbacina — 

HemicidaiidtP — 

Heraicidaris  iuturaescens  Clark 

Hypodiadema  elegans  Clark 

Goniopvgus  zitteli  Clark 

"Leptarbacia  argutus  Clark 

Diademina — 

Orthopsodpe — 

Orthopsis  planulata  Clark 

Orthopsis  occidentalis  Cragin 

Diadematidre — 

Pseudodiadema  emersoni  Clark 

Pseudodiadema  texanum  (Roemcr)  — 
Pseudodiadema  diatretum  (Morton)  . . . 

Heterodiadema  ornatum  Clark 

Cottaldia  rotula  Clark 

Hemipedina  charltoni  Cragin 

Diplopodiida^ — 

Diplopodia  taffi  Cratiin 

Diplopodia  streeru^itzi  Cragin 

Pedinidce — 

Stomechinus  hyatti  Clark 

Cyphosomatidfo — 

Cvphosoma  hilli  Clark 

CVphosoma  texanum  Roemer 

Cyphosoma  volanum  Cragin 


Triassic. 


Jurassic. 


Lower 
Creta- 
ceous. 


Upper 
Creta- 
ceous. 


X 
X 


X 
X 


X 
X 
X 

X 
X 


X 
X 
X 


INTRODUCTION. 
Geologic  distribution  of  the  Meiozoic  Echinodennata  of  the  United  States — Continued. 


13 


Triassic. 


Jurassic 


Lower 
Creta- 
ceous. 


Upper 
Creta- 
ceous. 


Echinoidea— Continued, 

Regular ia  ectobranchiata — Continued. 
Diademoidea— Continued. 
Diademina— Continued. 

Cyphosomatida}— Continued. 

C'optosoma  speciosum  Clark 

Coptosonia  mortoni  (de  Loriol) 

Micropsis  lineatus  Clark 

Echinina — 

Triplechinidse — 

Psainraeeliinus  cingulatus  Clark 

Pedinopsis  symmetrica  (Cragin) 

Pedinopsis  pondi  Clark 

Irregularia — 

Gnathostomata — 
Holect.vpina— 
Pygasteridai — 

Holectypus  pealei  Clark 

Holectypus  cragini  Clark 

Holectypus  plana tus  Roemer 

Clypeastrina — 
Clypeastridje — 

Echinanthus  mortonis  (Michelin) 

(?)  Scutellaster  eretaceus  Cragin 

Atelostomata — 
Asternata — 

Echinoneidfe — 

Pyriua  parryi  Hall 

Nucle'olitida?— 

Rotriopygus  alabamensis  Clark 

Echinobrissus  angustatus  Clark 

Echinobrissus  expansus  Clark 

Echinobrissus  te.xanus  Clark 

Trematopygus  cruciferus  (Morton) 

Cassidulidae— 

Pygurus  sp 

Pygurus  (?)  geometricus  (Morton) 

Catopygus  o\iformis  Conrad  

C^atopygus  pusillus  Clark 

Catopygus  williamsi  Clark 

Catopygus  sp 

Cassid'ulus  florealis  (Morton) 

(I^assidulus  ai-quoreus  Morton 

Cassidulus  micrococcus  Gabb 

Cassidulus  subquadratus  Conrad 

Cassidulus  subconicus  Clark 

Cassidulus  porrectus  Clark 

Cassidulus  stantoni  Clark 

C'assidulus  intermedins  Slocum 

Cassidulus  hemisphericus  Slocum 

Cassidulus  conoideus  Clark 

Cassidulus  abrnptus  Conrad 

(?)  Cassidulus  subangulatus  (Emmons) 

Sternata— 

Ecbinocorythidpe — 

A  nanchy  tes  ovalis  Clark 

Ananchytes  texana  Cragin 

Cardiaster  einctus  (Morton) 

Cardiaster  smocki  Clark 

Cardiaster  curtus  Clark 

Holastv  simplex  Shumard 

Spatangida? — 

Enallaster  texanus  (Roemer) 

Enallaster  obliquatus  Clark 

Heraiaster  elegans  Shumard 

Hemiaster  whitei  Clark 

Hemiaster  be.xari  Clark 

Hemiaster  comanchei  Clark 

Hemiaster  dalli  Clark 

Hemiaster  cahini  Clark 

Hemiaster  parastatus  (Morton) 

Hemiaster  Stella  (Morton) 

Hemiaster  ungula  (Morton) 

Hemiaster  texanus  Roemer 

Hemiaster  humphreysanus  Meek  and  Hayden  . 

Hemiaster  califomicus  Clark 

Hemiaster  beecheri  Clark 

Hemiaster  lacunosus  Slocum 

Hemiaster  kiimmeli  Clark 

Hemiaster  welleri  Clark 

Linthia  tumidula  Clark 

Linthia  variabilis  Slocum 


X 
X 
X 
X 
X 


X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 


X 
X 
X 
X 
X 
X 


X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 
X 


39800°— 15- 


14 


MESOZOIC   AND    CENOZOIC   ECHINODERMATA   OF    THE   UNITED    STATES. 
Stratigraphic  distribution  of  the  Cretaceous  Echinodermata  of  Texas. 


Trinity. 


Fredericks- 
burg. 


Washita. 


Austin. 


Taylor. 


Ophiogly pha  te.xana  Clark 

Cidaris  texanus  Clark 

Cidaris  dixieusis  Cragin 

Leiocidaris  hemigranosus  (Shumard). 

Salenia  texana  Credner 

Hyfiodiadema  elegans  Clark 

C.oniopygiis  zittoli  Clark 

Leptarbacia  argiitus  Clark  

Orthopsis  planulata  Clark 

Orthopsis  occidentalis  CragLn 

Pseudocliadema  texanura  {Roemer>.. 

Heterodiadema  ornatum  Clark 

Cottaldia  rotula  Clark 

Hemipedina  charltoni  Cragin 

Diplopodia  taffi  Cragin 

Diplopodia  steeruvitzi  Cragin 

Cyposma  hilli  Clark 

Cyphosoma  volanum  Cragin 

if  icropsis  lineatiis  Clark 

Pedinopsis  symmetrica  (Cragin) 

PedinopsLS  popdi  Clark 

Holectypus  planatns  Roemer 

Pyrina  parn  Hall 

Echinobrissus  augustatus  Clark 

Echinobrissus  texanus  Clark 

Ananchy tes  texana  Cragin 

Holastef  simplex  Shumard 

Enallaster  texanus  ( Roemer) 

Enallaster  obliquatiis  Clark 

Heraiaster  elegans  Shumard 

Hemiaster  wliitei  Clark 

Hemiaster  bexari  Clark 

Hemiaster  comanchei  Clark 

Hemiaster  dalli  Clark 

Hemiaster  cavini  Clark 

Hemiaster  texanus  Roemer 


X 

x' 


X 
X 


X 
X 
X 


X 
X 


X 
X 
X 


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INTKODUCTION.  17 

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18  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA   OF    THE   UNITED   STATES. 

1888, 

RoEMER,  F.,  Macraster,  eine  neue  Spatangoiden-Gattung  aus  der  Kreide  von  Texas:  Neues  Jahrb.,  1888,  vol.  1, 

pp.  191-195. 
• —  Ueber  eine  durch  die  Haufigkeit  Hippuriten-artiger  C'hamiden  ausgezeichtnete  Fauna  der  Oberturonen 

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330,  1892. 
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Craigin,  F.  W.,  A  contribution  to  the  invertebrate  paleontology  of  the  Texas  Cretaceous:  Geol.  Survey  Texas  Fourth 
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Hill,  R.  T.,  Paleontology  of  the  Cretaceous  formations  of  Texas;  The  invertebrate  paleontology  of  the  Trinity  divi- 
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WiLLisTON,  S.  W.,  The  Niobrara  Cretaceous  of  western  Kansas:  Kansas  Acad.  Sci.  Trans.,  vol.  13,  pp.  107-111,  2 
pis.,  1893. 

1894. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1893,  pp.  1-107,  1894. 

Cragin,  F.  W.,  The  Choctaw  and  Grayson  terranes  of  the  Arietina:  Colorado  Coll.  Studies,  vol.  5,  pp.  40-48,  1894. 

Descriptions  of  invertebrate  fossils  from  the  Comanche  series  in  Texas,  Kansas,  and  Indian  Territory:  Colorado 

Coll.  Studies,  vol.  5,  pp.  49-68,  1894. 
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diagram,  1894. 

1895. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1894,  pp.  1-55,  1895. 

Cragin,  F.  W.,  A  new  Cretaceous  genus  of  Clypeastridae:  Am.  Geologist,  vol.  15,  pp.  90,  91,  1895. 
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1896. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1895,  vol.  32,  pp.  1-70,  1896. 

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1897. 

Aguilera,  J.  G.,  Sinopsis  de  geologia  mexicana:  Inst.  geol.  Mexico  Bol.  4,  5,  and  6,  pp.  187-250,  1897. 

Clark,  W.  B.,  Upper  Cretaceous  formations  of  New  Jersey,  Delawai'e,  and  Mai'yland:  Geol.  Soc.  America  Bull.,  vol.  8, 

pp.  31.5-318,  Pis.  XL-L,  1897. 
Williston,  S.  W.,  The  Kansas  Niobrara  Cretaceous:  Kansas  Univ.  Geol.  Survey,  vol.  2,  pp.  242,  243,  1897. 


INTKODTJCTIOH'.  19 

1898. 

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Clark,  W.  B.,  Report  upon  the  Upper  Cretaceous  formations:  New  Jersey  Geol.  Survey  Ann.  Rept.  for  1897,  pp.  161- 

210,  1898. 
Hill,  R.  T.,  and  Vaughan,  T.  W.,  Geology  of  the  Edwards  Plateau  and  Rio  Grande  plain  adjacent  to  Austin  and  San 

Antonio,  Tex.  with  reference  to  the  occurrence  of  underground  waters:  U.  S.  Geol.  Siu'vey  Eighteenth  Ann. 

Rept.,  pt.  2,  pp.  193-321,  Pis.  XXI-LXIV,  24  figs.,  1898. 
Logan,  W.  N.,  The  invertebrates  of  the  Benton,  Niobrara,  and  Fort  Pierre  groups:  Kansas  Univ.  Geol.  Survey,  vol.  4, 

pt.  1,  pp.  431-518,  1898. 
Weed,  W.  H.,  and  Pirsson,  L.  V.,  Geology  and  mineral  resources  of  the  Judith  Mountains  of  Montana:  U.  S.  Geol. 

Survey  Eighteenth  Ann.  Rept.,  pt.  3,  pp.  437-616,  Pis.  LIX-LXXXVII,  25  figs.,  1898. 

1899. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  tor  1898,  vol.  35,  pp.  1-73,  1899. 

BosE,  Emilio,  Geologia  de  los  alrededores  de  Orizaba:  Inst.  geol.  Mexico  Bol.  13,  pp.  1-52,  1899. 

Darton,  N.  H.,  Jurassic  formations  of  the  Black  Hills,  S.  Dak.:  Geol.  Soc.  America  Bull.,  vol.  10,  pp.  383-396, 

Pis.  XLII-XLIV,  1899. 

Springer,  Frank,  Notice  of  a  new  discovery  concerning  Uintacrinus:  Am.  Geologist,  vol.  24,  p.  92,  1899. 

Stanton,  T.  W.,  Mesozoic  fossils  of  the  Yellowstone  National   Park:  U.  S.  Geol.  Survey  Mon.  32,  pt.  2,  pp.  600- 

640,  1899. 

1900. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1S99,  vol.  36,  pp.  1-101,  1900. 

A  treatise  on  zoology,  pt.  3,  The  Echinodermata,  1900. 

Beecher,  C.  E.,  On  a  large  slab  of  Uintacrinus  from  Kansas:  Am.  Jour.  Sci.,  4th  ser.,  vol.  9,  pp.  267-268,  Pis.  Ill,  IV, 

1900. 
Holmes,  J.  A.,  The  deep  well  at  Wilmington,  N.  C:  Science,  new  ser.,  vol.  11,  pp.  128-130,  1900. 
Knight,  W.  C,  A  preliminary  report  on  the  artesian  basins  of  Wyoming:  Wyoming  Exper.  Sta.  Bull.  45,  pp.  105-251, 

Pis.  I-XIV,  1900. 

Jurassic  rocks  of  southeastern  Wyoming:  Geol.  Soc.  America  Bull.,  vol.  11,  pp.  377-388,  PL  XXIII,  1900. 

Logan,  W.  N.,  The  stratigraphy  and  invertebrate  faunas  of  the  Jurassic  formation  in  the  Freezeout  Hills  of  Wyoming: 

Kansas  Univ.  Quart.,  vol.  9,  pp.  109-134,  Pis.  XXV-XXXI,  1900. 
Springer,  F.,  LTintaciinus;  its  structure  and  relations:  Mus.  Comp.  Zool.  Mem.,  vol.  25,  No.  1,  90  pp.,  8  pis.,  3  figs.,  1900. 
Vaughan,  T.  W.,  Reconnaissance  in  the  Rio  Grande  coal  fields  of  Texas:  U.  S.  Geol.  Survey  Bull.  164,  100  pp.,  11  pis., 

1900. 
Villareal,  F.,  Paleontologia  sudamericana;  Echinodermata:  Revist.  cienc.  Lima,  vol.  3,  pp.  129-132,  1900. 

1901. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1900,  pp.  1-153,  1901. 

Darton,  N.  H.,  Preliminary  description  of  the  geology  and  water  resources  of  the  southern  half  of  the  Black  Hills  and 
adjacent  regions  in  South  Dakota  and  Wyoming:  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  4,  pp.  489-599, 
Pis.  LVIII-CXII,  28  figs.,  1901. 

Hill,  R.  T.,  Geogi'aphy  and  geology  of  the  Black  and  Grand  prairies,  Texas,  with  detailed  descriptions  of  the  Creta- 
ceous formations  and  special  reference  to  artesian  waters:  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  7,  pp. 
86-386,  Pis.  XIV-LIV,  56  figs.,  1901. 

Lindgren,  W.,  Trias  in  northeastern  Oregon:  Science,  new  ser.,  vol.  13,  pp.  270,  271,  1901. 

1902. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1901,  vol.  38,  pp.  1-99,  1902. 

Anderson,  F.  M.,  Cretaceous  deposits  of  the  Pacific  coast:  California  Acad.  Proc,  3d  ser..  Geology,  vol.  2,  No.  1,  154 

pp.,  12  pis.,  1902. 
H[ovey],  E.  0.,  A  remarkable  slab  of  fossil  crinoids:  Am.  Mus.  Nat.  Hist.  Jour.,  vol.  2,  pp.  11-14,  1  pi.,  1  fig.,  1902. 

1903. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1902,  vol.  39,  pp.  1-88,  1903. 

Dougla.ss,  E.,  Astropecten  (?)  montanus — a  new  starfish  from  Fort  Benton — and  some  geological  notes:  Carnegie  Mus. 

Pub.  20,  Carnegie  Mus.  Ann.,  vol.  2,  pp.  5-8,  1  fig.,  1903. 
Whiteaves,  J.  L.,  On  some  additional  fossils  from  the  Vancouver  Cretaceous,  with  a  rcAdsed  li,st  of  the  species  tliere 

found;  Mesozoic  fossils:  Geol.  Survey  Canada,  vol.  1,  pt.  5,  pp.  309-415,  Pis.  XL-LI,  1903. 

1904. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1903,  vol.  40.  pp.  1-105,  1904. 

Whiteave.s,  J.  F.,  Uintacrinus  and  Hemiaster  in  the  Vancouver  Cretaceous:  Am.  Jour.  Sci.,  4th  ser.,  vol.  18,  pp.  287- 

289,  1904. 
Schuchert,  Charles,  A  noteworthy  crinoid:  Smithsonian  Misc.  Coll.,  vol.  45,  p.  4.50,  PI.  CIII,  1904. 


20  MESOZOIC   AND    CENOZOIC   ECHINODEEMATA    OF    THE   UNITED    STATES. 

1905. 

Bather,  F.  A.,  Echinoderma:  Zool.  Record  for  1904,  vol.  41,  pp.  1-96,  1905. 

Cragin,  F.  W.,  Paleontology  of  the  Malone  Jurassic  formation  of  Texas:  U.  S.  Geol.  Sur\'ey  Bull.  266,  172  pp.,  29  pis., 

1905. 
Johnson,  C.  W.  ,  Annotated  list  of  the  types  of  invertebrate  Cretaceous  fossils  in  the  collection  of  the  Academy  of  Natural 

Sciences,  Philadelphia:  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  pp.  4-28,  1905. 
Welleb,  Stuakt,  a  fossil  starfish  from  the  Cretaceous  of  Wyoming:  Jour.  Geology,  vol.  13,  pp.  257,  258,  fig.  1,  1905. 

1906. 

Grant,  M.,  Echinoderma:  Zool.  Record  for  1905,  pp.  1-92,  1906. 

1907. 

Weller,  Stuart,  A  report  on  the  Cretaceous  paleontology  of  New  Jersey;  Echinodermata:  Geol.  Survey  New  Jersey, 
pp.  275-305,  Pis.  VI-XVIII,  1907. 

1909. 

Bassler,  R.  S.,  Some  noteworthy  accessions  to  the  division  of  invertebrate  paleontology  in  the  National  Museum: 

Smithsonian  Misc.  Coll.,  vol.  52,  pp.  267-269,  Pis.  XVII,  XVIII,  1909. 
Lambert,  J.,  and  Thiery,  P.,  Essai  de  nomenclature  raisonn^e  des  echinides,  1909. 
Slocum,  a.  W.,  Newechinoids  from  the  Ripley  group  of  Mississippi :  Field  Mus.  Nat.  Hist.  Pub.  134,  Geol.  ser.,  vol.  4, 

No.  1,  pp.  1-16,  Pis.  I-III,  1909. 
Springer,  Frank,  A  new  American  Jurassic  crinoid:  U.  S.  Nat.  Mus.  Proc,  vol.  36,  pp.  179-190,  PI.  IV,  1909. 

1910. 

Clark,  W.  B.,  and  Twitchell,  M.  W.,  Geological  distribution  of  the  Mesozoic  and  Cenozoic  Echinodermata  of  the 
United  States:  Geol.  Soc.  America  Bull.,  vol.  20,  1908,  pp.  686-688,  1910. 

1911. 

Springer,  Frank,  Some  new  American  crinoids:  Mus.  Comp.  Zool.  Mem.,  vol.  25,  No.  3,  pp.  117-161,  Pis.  I-VI, 
1911. 

Note. — A  number  of  contributions  have  appeared  during  the  progress  of  this  report  through  the  press,  the  results 
of  which  can  not  be  fully  incorporated  in  the  following  pages,  although  footnotes  concerning  some  of  them  have  been 
inserted.    Among  the  more  important  of  these  publications  are: 

Jackson,  R.  T.,  Phylogeny  of  the  Echini,  with  a  revision  of  Paleozoic  species:  Boston  Soc.  Nat.  Hist.  Mem.,  vol.  7, 
491  pp.,  76  pis.,  258  figs.,  1912. 

Jackson  proposes  the  generic  name  Centrechinus  to  replace  Diadema,  thus  changing  the  names  of  family  and 
order  to  which  the  genus  belongs. 
Smith,  J.  P.,  The  Middle  Triassic  marine  invertebrate  fannies  of  North  America:  U.  S.  Geol.  Survey  Prof.  Paper  83, 
254  pp.,  99  pis.,  1914. 

Smith  refers  to  Pentacrinus  cf.  P.  asteriscus  Meek  and  Hayden,  in  material  from  the  Pit  shale  of  California. 


TRIASSIC   ECHINODERMATA.  . 
Class  CKINOIDEA. 
Subclass  DICYCLICA. 
Order  INADUNATA. 
Suborder  DENDROCRINOIDEA. 
Family  PENTACRINID^. 
Genus  ISOCRINUS  von  Meyer. 
IsocRiNtJS  SMiTHi  Clark,  n.  sp. 
Plate  I,  figures  la-b. 

Determinative  characters. — Column  composed  of  small  moderately  thick  pentagonal  joints, 
with  sharp  reentering  angles  on  the  large  specimens.     Column  perforated  by  small  canal. 

Dimensions. — Column:  Diameter  of  joint  ^  to  2  millimeters;  length  of  joint  J  to  1  milli- 
meter. 

Description. — The  joints  are  generally  separated  and  more  or  less  weathered,  being  found 
in  great  numbers  on  many  leached  surfaces  of  limestone.  The  largest  and  best-preserved  speci- 
mens are  moderately  thick  and  show  sharp  reentering  angles.  The  crenulated  ridges  are  gen- 
erally so  badly  weathered  that  their  characters  are  obscured,  but  they  are  broadly  petaloid 
with  rather  sharp  angles  at  their  outer  extremities.  All  the  Lower  Triassic  forms  are  assigned 
to  this  species.  Some  minor  differences  appear  among  the  specimens  examined,  however,  and 
more  than  one  species  may  be  represented. 

Locality. — One  mile  west  of  Paris,  Bear  Lake  County,  Idaho. 

Geologic  horizon. — Columbites  zone,  Thaynes  limestone,  Lower  Triassic,  150  feet  above 
strata  with  Meekoceras  fauna,  but  below  beds  containing  typical  Lower  Triassic  forms. 

Collections. — U^  S.  National  Museum  (31184);  Leland  Stanford  Junior  University. 

IsocKiNUS  CALiFORNicus  Clark,  n.  sp. 

Plate  I,  figures  2a-c 

Determinative  cTiaracters. — Column  composed  of  medium-sized  rather  thin  pentagonal  joints, 
with  sharp  reentering  angles.  The  crenulated  ridges  are.  rather  narrowly  petaloid,  and  each 
area  is  sharply  terminated  at  its  outer  extremity.     Colimin  perforated  by  large  canal. 

Dimensions. — Column:  Diameter  of  joint  2  to  5  millimeters;  length  of  joint  J  to  1  milli- 
meter. 

Description. — Several  specimens  of  isolated  column  joints  of  Isocrinus  from  the  Upper  Trias- 
sic rocks  of  California,  which  may  or  may  not  belong  to  a  single  species,  have  been  examined  by 
the  author.  Differences  in  the  size  of  the  joints  and  the  sharpness  of  the  reentering  angles 
appear,  but  they  may  be  due  to  difference  in  age  of  the  individuals  represented  or  by  the  differ- 
ent positions  of  the  joints  on  the  stem.  In  the  absence  of  more  satisfactory  criteria,  therefore,  all 
the  Upper  Triassic  Pentacrini  examined  have  been  referred  to  this  species.  The  majority  of 
specimens  studied  are  not  of  large  size,  although  considerably  larger  than  /.  smithi  of  the  Lower 
Triassic.  Most  of  them  show  deep  reentering  angles.  The  crenulated  ridges  are  obscure  in 
many  specimens,  but  where  well  preserved  are  rather  narrowly  petaloid,  and  each  area  is  sharply 
terminated  at  its  outer  extremity.     A  large  well-marked  canal  perforates  the  column. 

21 


22  MESOZOIC    AND    CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

Locality. — Two  and  one-half  miles  west  of  Rountl  Mountain,  Shasta  County  (type),  and  at 
Rush  Creek,  Plumas  County,  Cal. 

Geologic  horizon. — "Cedar  formation,"  Upper  Triassic. 

Collections. — U.  S.  National  Museum  (31185);  Leland  Stanford  Junior  UniTersity. 

ISOCRINUS    Sp. 

Pcntacnnus  astrriscus  (f)  Hall  and  'Whitfield,  1877,  U.  S.  Geol.  Expl.  40th  Par.  Final  Rept.  vol.  4,  pp.  280,  281,  PI.  VI, 
fig.  l(i. 

Hall  and  Wliitfield  examineil  several  column  joints  of  supposed  Pentacrinus  collected  by 
Arnold  Hague  of  the  40th  Parallel  Survey  "in  limestone  of  supposed  Triassic  age, -associated 
with  Sfiriferina  homfrayi  and  Terehratula  humboldtensis  Gabb,  near  Dun  Glen  Pass,  Pahute 
Range,  Nevada,"  which  they  doubtfully  referred  to  P.  asteriscus  Meek  and  Hayden  of  the  Juras- 
sic of  the  Rocky  Mountain  region.  They  note  certain  differences  "in  the  more  obtuse  points  of 
the  star,  and  the  filling  up  of  the  angles  between  the  points,  and  also  in  the  broader  form  of  the 
elliptical  figures  on  the  articulating  surfaces  of  the  disks."  They  state  that  although  these  fea- 
tures are  not  constant  the  form  is  larger  than  P.  asteriscus,  and  that  better  material  would  doubt- 
less show  it  to  be  another  species.  It  is  evident  that  this  form  can  not  be  safely  referred  to  the 
Jurassic  species  P.  asteriscus,  but  as  the  author  has  not  had  access  to  further  material  it  is  simply 
referred  to  the  genus  Isocrinus  without  specific  description.  The  limestones  at  Dun  Glen  Pass 
were  correlated  with  the  base  of  the  Star  Peak  formation,  and  more  recent  work  has  confirmed 
this  determination. '     The  Star  Peak  formation  is  of  both  !Middle  and  Upper  Triassic  age. 

Locality. — Dun  Glen  Pass,  Pahute  Range,  Nevada. 

Geologic  horizon. — Limestone  of  Dun  Glen  Pass,  Middle  Triassic. 

Collection. — U.  S.  National  Museum. 

Family  ENCRINID^. 

Genus  ENCRINUS  C.  F.   Schulze. 

Encrinus  hyatti  Clark,  n.  sp. 

Plate  I,  figures  3a-b. 

Determinative  characters. — Column  composed  of  large,  thin,  round  to  oval  joints.  Surfaces 
of  joints  covered  with  fine,  bifurcating  striations,  producing  a  close  suture.  Column  perforated 
with  canal  of  rather  small  size. 

Dimensions. — Column:  Diameter  of  joint  5  to  10  millimeters;  length  of  joint  1  to  3  milli- 
meters. 

Description. — Several  specimens  of  casts  of  the  column  joints  of  Encrmus  have  been  exam- 
ined by  the  author  from  a  single  Upper  Triassic  locality  in  California.  The  column  itself  is 
wanting  in  every  specimen,  but  the  cast  of  the  "close  surface"  is  very  perfect,  much  more  so  than 
the  cast  of  the  outer  surface,  which  in  all  specimens  has  lost  its  distinctive  features.  Most  of  the 
casts  show  a  somewhat  oval  outline,  which  may  be  due  to  compression,  as  the  stems  of  most  of 
the  species  belonging  to  this  genus  are  round. 

The  joints  surpass  considerably  in  size  those  of  aiiy  other  crinoid  form  in  the  American 
Mesozoic.  The  round  to  oval  shape  of  the  "close  surface"  of  the  specimens  and  the  fine  bifur- 
cating striations  thereon  are  highly  distinctive,  enabling  the  relations  of  the  form  to  be  readily 
determined  even  in  small  fragments.  All  the  specimens  evidently  belong  to  the  same  species. 
A  rather  small  canal  is  present. 

Locality. — Oscar  tunnel,  2i  miles  southeast  of  Longville,  Plumas  County,  Cal. 

Geologic  horizon. — "Cedar  formation,"  Upper  Ti'iassic. 

Collection.~1J.  S.  National  Museum  (31186). 

•  Duruig  the  progress  of  this  report  tlircugh  the  press  a  paper  by  J.  P.  Smilh  (The  Middle  Triassic  marine  invertebrate  faunas  of  North 
America:  U.  S.  Geol.  Survey  Prof.  Paper  S3,  1914)  has  appeared,  in  which  he  says  (p.  14S):  "A  species  identical  with  that  of  Dun  Glen,  Nev., 
occurs  iu  the  Pit  shale  of  California,  associated  with  a  poor  fauna  characteristic  of  the  Middle  Triassic."  It  is  referred  to  Pentacrinus  cf. 
P.  asteriscus  Meek  and  Hayden. 


TEIASSIC    ECHINODEEMATA,  23 

Class  STELLEROIDEA. 

Subclass  OPHIUKOIDEA. 

Order  ZYGOPHIUR^. 

Family  AMPHIURID.E. 

Genus  ASPIDUBA  Agassiz. 

AspiDURA  ( ?)  iDAHOENSis  Clark,  n.  sp. 

Plate  I,  figure  4. 

Determinative  characters. —  Casts  of  small  forms,  with  short  arms.     Very  poorly  preserved. 

Dimensions. — Diameter  of  disk  5  to  7  millimeters;  length  of  arms  10  to  25  millimeters. 

Description. — Three  individuals  of  this  species,  all  in  a  very  imperfect  state  of  preservation, 
have  been  examined.  They  occur  as  partial  casts  of  the  disk  and  rays.  The  characteristics  of 
none  of  the  plates  can  be  seen.  The  general  outlme  of  the  disk  and  rays  remains  constant  in  all 
the  specimens,  which  evidently  belong  to  the  same  species. 

Locality. — One  and  one-half  miles  west  of  Paris,  in  the  fiLrst  canyon  north  of  Paris  Canyon, 
Bear  County,  Idaho. 

Geologic  horizon. — Thaynes  limestone.  Lower  Triassic. 

Collection.— V.  S.  National  Museum  (31187). 

Class  ECHINOIDEA. 

Subclass  REGULARIA  ENDOBRANCHIATA. 

Order  CIDAROIDEA. 

Family  CIDARID.E. 

Genus  CIDARIS  Leske. 

CiDARIS   SHASTENSIS   Clark,  n.  Sp. 

Plate  I,  figure  5. 

Determinative  characters. — Test  apparently  large.  Interambulacral  areas  wide.  Tubercles 
large,  circular,  with  depressed  areolas ;  miliary  space  large. 

Dimensions. — Width  of  fragment  10  millimeters;  height  of  fragment  6  millimeters. 

Description. — The  single  fragmentary  interambulacral  plate  found  indicates  that  this  species 
possessed  a  test  of  considerable  size.  The  interambulacral  areas  are  wide,  the  tubercles  large, 
circular,  and  mth  depressed  areolas.  The  miliary  space  is  large.  The  plate  is  probably  from 
near  the  ambitus.  The  broken  tubercle  renders  it  impossible  to  say  whether  the  mamelon  was 
perforated  or  not.     There  is  no  trace  of  the  plates  of  the  ambulacral  area. 

Related  forms. — Species  is  shown  by  the  wide  miliary  space  to  be  cjuite  distinct  from  C.  dil- 
leri.     It  is  evidently  a  new  species. 

Locality. — Two  and  one-half  miles  west  of  Round  Mountain,  Shasta  County,  Cal. 

Geologic  horizon. — "Cedar  formation,"  Upper  Triassic. 

Collection. — U.  S.  National  Museum  (31188). 

CiDARis  DiLLEEi  Clark,  n.  sp. 

Plate  I,  figure  6. 

Determinative  characters. — Test  apparently  of  medium  size;  ambulacral  areas  narrow,  flexu- 
ous,  with  two  rows  of  granules  between  the  poriferous  avenues;  interambulacral  areas  of  mod- 
erate width.  Tubercles  of  medium  size  with  oval  areolas ;  boss  crcnulatcd ;  mamelon  perforated ; 
miliary  space  naiTow. 


24  MESOZOIC   AND    CENOZOIC    ECHINODERMATA   OF    THE    UNITED    STATES. 

Dimensions. — Test :  probable  diameter  about  35  millimetere ;  probable  height  about  25  milM- 
nieters:  size  of  iuterambulacral  jjlate  near  ambitus:  Width  8  millimeters;  height  6  millimeters. 

Description. — The  portion  of  the  test  studied  in  the  single  specimen  of  this  species  thus  far 
found  is  in  the  form  of  a  cast  of  the  exterior  of  three  interambulacral  plates  with  their  adjacent 
ambulacral  plates  on  either  side.  The  casts  afford  a  very  perfect  mold  of  the  more  important 
features  of  these  plates,  which  are  apparently  below  the  ambitus,  in  this  respect  differing  from 
the  specimen  of  C.  shastensis,  which  comes  apparently  from  nearer  the  ambitus. 

The  test  was  probably  of  medium  size.  The  ambulacral  areas  are  narrow,  strongly  flexuous, 
with  two  rows  of  small  granules  between  the  poriferous  avenues.  The  interambulacral  areas  are 
of  moderate  width,  being  largely  occupied  by  the  tubercles,  which  are  of  medium  size.  The 
areolas  are  oval,  the  boss  crenulated  and  the  mamelon  perforated.  The  miliary  space  is  very 
narrow,  very  few  granules  being  found  on  the  area. 

Related  forms. — Form  is  shown  by  its  snaall  miliary  areas  to  be  quite  distinct  from  C. 
shastensis.     It  is  evidently  a. distinct  species. 

Locality. — Two  and  a  half  mUes  west  of  Round  Mountain,  Shasta  County,  Cal. 

Geologic  horizon. — "Cedar  formation,"  Upper  Triassic. 

Collection. — U.  S.  National  Museum  (31189). 


JURASSIC  ECHINODERMATA. 

Class  CRINOIDEA. 

Subclass  DICYCLICA. 

Order  INADUNATA. 

Suborder  DENDROCRINOIDEA. 

Family  PENTACRINID^. 

Genus  ISOCRINUS  von  Meyer. 

IsocRiNus  KNiGHTi  Springer. 

Plate  II,  figures  1-13;  Plate  III,  figures  la-d. 

7 Pentacrinites  ash'riscus  Meek  and  Hayden,  1865,  Paleontology  Upper  Missouri:  Smithsonian  Contr.,  vol.  14  (172), 

p.  67,  text  tig.  (not  PI.  Ill,  figs.  2a-b). 
Pentacriniis  asteriscus  Knight,  1900,  Geol.  Soc.  America  Bull.,  vol.  11,  p.  386. 
"i Penlacrinus  asteriscus  Logan,  1900,  Kansas  Univ.  Quart.,  vol.  9,  p.  119,  PI.  XXV,  figs.  4-7. 
Isocrinus  hnighti  Springer,  1909,  U.  S.  Nat.  Mus.  Proc,  vol.  36,  pp.  179-190,  PI.  IV,  figs.  1-13. 

Determinative  characters. — Springer  describes  the  species  as  follows: 

Specimens  of  moderate  size. 

Stem  smooth,  long,  slightly  increasing  in  diameter  distally;  pentagonal  with  straight  sides,  except  at  the  proximal 
end,  where  for  the  first  few  immature  internodes  the  younger  joints  are  stellate.  Internodals  about  14,  but  varying 
from  12  to  17  in  the  mature  parts;  distinctly  crenulated  at  the  margins;  nodals  not  enlarged,  scarcely  distinguishable 
from  the  others  except  by  the  cirrus  sockets;  these  are  rather  shallow,  not  extending  to  the  hjrpozygal,  or  infranodal 
joint,  but  usually  encroaching  upon  the  supranodal,  in  which  case  the  apposed  faces  of  these  two  joints  are  more  or  less 
indented,  producing  a  marked  stellate  outline.  Conformably  to  this  structure  the  cirri  are  directed  upward.  Inter- 
articular  pores  extending  to  the  fifth  internode.  Cirri  in  whorls  of  five;  round,  long,  and  slender,  composed  of  40 
joints  or  more;  the  proximal  ones  relatively  short  and  broad — about  one-third  as  long  as  wide — tapering  rapidly  to 
about  half  their  breadth,  and  doubling  in  length  in  the  first  8  or  10  joints,  beyond  which  they  continue  uniformly  about 
as  long  as  wide  to  the  end;  terminal  claw  not  preserved.  Angles  of  stem  interradial;  cirri  radial;  axial  canal  iu  stem 
small,  obtusely  pentagonal,  and  apparently  interradial  in  position. 

Cup  forming  a  low  cone,  without  any  downward  projection  or  basals  or  radials.  Infrabasals  well  defined,  fillin" 
half  the  diameter  of  the  column  facet  and  entirely  covered  by  the  proximal  columnal.  Basals  large,  smooth,  visible 
in  pentagonal  outline,  and  in  full  contact  exteriorly  b\  their  lateral  faces;  they  form  a  closed  ring,  not  protuberant 
but  flush  with  the  plane  of  the  radials,  and  about  equal  to  them  in  height.  Radials  forming  also  a  ring  continuous  with 
basals.  PrLmibrachs  two,  united  by  articulation  apparently  bifascial.  Arms  simple,  or  bifurcating  once  from  the 
sixteenth  to  the  thirtieth  IIBr,  thus  varying  from  10  to  20;  they  are  long,  slender,  with  strongly  oblique  articulatiii" 
faces,  and  they  extend  to  upward  of  90  brachials.  Syzygies  at  IIBr  3  -f  4,  and  beyond  throughout  the  arm  at  intervals 
of  about  5  to  10  brachials.  Pinnules  long,  rounded,  composed  of  elongate  joints,  15  or  more  in  the  distal  pinnules, 
but  the  number  in  the  proximal  ones  not  observable.     Disk  unknown. 

Dimensions. — Height  of  crown  65  millimeters;  length  of  cirrus  of  40  joints  32  milUmeters; 
length  of  longest  stem  preserved  140  millimeters;  diameter  of  stem  at  second  internode  2  milli- 
meters; diameter  of  stem  at  tenth  internode  2.5  millimeters. 

Description. — The  first  complete  crown  of  this  species  was  obtained  by  the  late  W.  C.  Ivnight, 
of  the  University  of  Wyoming,  in  1S99,  in  the  course  of  his  investigations  of  the  Morrison  forma- 
tion near  Medicine  Bow,  Wyo.  He  found  one  very  complete  specimen  and  numerous  stems  and 
fragments  of  arms  on  several  small  slabs  of  argillaceous  Umestone  that  lay  in  the  debris.  He 
referred  the  crown  to  Pentacrlnus  asteriscus.  Some  additional  material  obtained  the  following 
year  has  afforded  several  additional  crowns.  All  the  specimens  were  fuially  placed  for  study 
in  the  hands  of  Spriirger,  who  finds  reasons  for  beheving  that  the  form  belongs  to  Isociinus  and 
not  Pentaciinus. ' 


1  A  new  American  Jurassic  crinoid:  U.  S.  Nat.  Mus.  Proc,  Tol.  36,  pp.  179-190,  PI.  IV,  1909. 

25 


26  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA   OF    THE   UNITED    STATES. 

Springer  in  describing  this  species  makes  the  following  interesting  comparison  with  recent 
species: 

The  stem  has  a  considerable  resemblance  to  that  of  /.  dccorus,  except  in  the  disposition  of  the  cirri.  It  must  have 
been  quite  long,  as  the  longest  portion,  preserved  to  a  distance  of  140  millimeters,  shows  little  sign  of  any  rounding.  It 
is  rather  more  pentagonal  for  equivalent  distances.  The  cirri  are  very  long  and  slender;  the  taper  near  the  base  from 
short  and  wide  joints  to  long,  narrow,  and  equal  ones  is  quite  marked.  The  most  perfect  one  has  44  joints,  and  this 
was  probably  near  the  maximum.  The  interesting  thing  about  the  cirri,  however,  is  the  fact  that  they  are  directed 
upward  instead  of  downward  or  outward.  In  consequence  the  sockets  do  not  extend  to  the  infranodal  (hj-pozygal) 
joint,  but  slope  upward  toward  the  supranodal,  the  lower  margin  of  which  is  often  incised  by  them.  This  is  more  or 
less  the  case  in  the  genus  Metacrinus,  but  is  not  usual  in  the  recent  species  of  Isocrinus,  most  of  which  have  the  cirri 
directed  downward,  though  in  some,  as  /.  asteria  and  /.  icyville-lhomsoni,  the  socket  is  confined  to  the  nodal  joint,  and 
the  cirri  are  given  off  about  horizontally. 

The  basals,  as  shown  by  the  five  specimens  figured  and  three  others,  are  quite  uniform  in  their  form  and  propor- 
tions. They  form  with  the  radials  a  low  funnel,  with  smooth  or  slightly  rounded  sides,  and  without  protuberance  or 
projection  of  any  kind.  They  are  connected  exteriorly  by  their  lateral  faces,  giving  a  pentagonal  outline  and  forming 
a  closed  ring  [PI.  II,  fig.  3a],  as  in  the  type  for  which  Forbes  proposed  the  genus  Cainocrinus,  instead  of  appearing  as 
mere  triangular  points  separated  from  each  other  by  the  radials  and  tending  more  or  less  to  project  downward  over  the 
proximal  column  joints,  as  in  more  recent  species. 

The  bifurcation  of  the  arms  so  far  beyond  the  axillary  IBr  is  an  unusual  feature,  occurring  in  the  largest  specimen 
at  the  twenty-seventh  to  the  thirtieth  brachial  [Pl.II,  fig.  1],  and  in  other  specimens  from  the  sixteenth  to  the  twenty- 
third.  I  know  of  no  pentacrinoid  in  which  arm  division  takes  place  so  high  up;  nor  in  fact  any  inadunate  crinoid,  the 
nearest  approach  to  it  being  found  in  the  Carboniferous  genus  Poteriocrinus.  There  is  little  tendency  of  the  arms  to 
spread  out,  but  they  are  long  and  slender,  tending  rather  to  lie  in  a  bundle.  The  general  aspect  of  calyx  and  arms  is 
somewhat  like  that  of  I.naresianus,  which  it  also  resembles  in  the  number  and  regularity  of  the  syzygies,  which  is 
unusual  in  the  Pentacrinidse.  I  can  trace  them  in  two  arms  of  specimen  A  [PL  II,  fig.  1]  part  way,  and  in  one  to  the 
end,  and  can  distinguish  them  in  the  distal  portion  of  some  other  arms.  Beginning  at  IIBr  3  +  4,  they  occur  at  inter- 
vals of  mostly  about  10  brachials,  but  sometimes  4,  5.  or  6.  I  give  a  figure  of  the  pair  next  to  the  last,  being  about 
brachials  79  -t-  80  of  that  arm  [PI.  II,  fig.  la]. 

Related  forms. — Springer  states  that  the  stem  joints  of  /.  Tcnighti  — 

are  uniformly  different  from  the  much  larger  ones  on  which  P.  asteriscus  was  founded,  and  from  the  Utah  specimen 
referred  by  Dr.  White  to  P.  asteriscus  '  but  afterwards  separated  from  it  by  Dr.  W.  B.  Clark  under  the  name  Pinta- 
crinus  lohilei,  because  of  its  alternating  joints.  Clark's  camparison  was  made  chiefly  with  the  Red  Buttes  specimen  of 
P.  asteriscus  (?),  but  the  separation  is  doubtless  well  founded,  nevertheless,  as  the  character  on  which  he  bases  it  is 
clear  in  his  specimen,  and  cannot  be  shown  in  the  type  of  P.  astcriseiis.  The  difference  between  the  stem  of  our  species 
and  that  of  P.  whitei  is  similar  to  that  between  the  recent  /.  dccorus  and  I.  parrx,  which  is  fairly  constant. 

The  most  nearly  related  European  species  that  I  know  of  is  de  Loriol's  "Pentacrinus"  beaugrandi  from  the  Upper 
Jurassic,  Portlandian  stage,  near  Boulogne-sur-Mer,  France.-  This  was  the  only  Crinoid  known  to  the  author  from 
the  Portlandian  stage,  and  it  is  the  species  which  he  originally  proposed  to  separate  from  the  other  Pentacrinidse  on 
account  of  having  a  closed  ring  of  basals,  under  the  name  Picteticrinus.  In  this  he  found  himself  anticipated  by  the 
Cainocrinus  of  Forbes,  and  in  the  work  last  cited,  page  281,  he  abandoned  the  distinction,  and  referred  the  species  to 
Pentacrinus  (sensu  P.  H.  C.  ).  It  has  similar  large  basals,  but  the  arms  branch  lower  down,  the  stem  is  more  sharply 
stellate  in  corresponding  portions,  and  the  cirri  much  more  delicate.  The  stem  is  preserved  to  the  fourth  internode, 
which  has  8  internodals,  whereas  ours  has  14  at  the  same  stage. 

Pentacrinus  (Cainocrinus)  andrex  Desor  ^  is  similar  to  the  French  species,  but  with  shorter  basals  and  shorter 
internodes. 

Localities.— Medicine  Bow  (type)  and  Red  Buttes,  Wyo. 

Geologic  horizon. — Sundance  formation  (Shirley  stage  of  Knight),  Upper  Jurassic. 

Collection. — U.  S.  National  Museum  (682) . 

Genus  PENTACRINUS  Blumenbach. 

Pentacrinus  asteriscus  Meek  and  Hayden. 
Plate  III,  figure  2. 
Pentacrinus  asteriscus  Meek  and  Hayden,  1858,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  10,  p.  49. 
Pentacrinus  asteriscus  Meek  and  Hayden,  1860,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  12,  p.  419. 
Pentacrinus  asteriscus  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  27. 

Pentacrinites  asteriscus  Meek  and  Hayden,  1865,  Paleontology  Upper  Missouri,  Smithsonian  Contr.,  vol.  14  (172),  p.  67, 
PI.  Ill,  figs.  2a,  2b. 


1  U.  S.  Geol.  Survey  Bull.  97,  p.  27, 1S93. 

2  Mon.  «tage  Jur.  Boulogne-sur-Mer,  p.  298,  PI.  XXVI,  flgs.  23-25, 1875;  Paleontologie  frangaise,  Crinoides,  vol.  11,  pt.  2,  p.  278,  PI.  CLXXXI, 
figs.  1-3. 

3  De  Loriol,  Crin.  toss,  de  la  Suisse,  p.  112. 


JURASSIC    ECHINODEEMATA.  27 

Pentacrinites  asteriseiis  'Wliitfield,  1880,  Paleontology  of  Black  Hills  of  Dakota:  U.  S.  Geog.  and  Geol.  Survey  Kocky 

Mtn.  Region,  p.  345,  PI.  Ill,  figs.  1,  2. 
Pentacrinns  asteriscus  Peale,  1880,  U.  S.  Geol.  and  Geog.  Survey  Terr.  Bull.,  vol.  5,  No.  1,  p.  120. 
Pentacrinus  asteriscus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Pentacrinus  asteriscus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  26,  27,  PL  II,  figs.  2a-d. 
Pentacrinus  asteriscus  Weed  and  PLrsson,  1898,  U.  S.  Geol.  Survey  Eighteenth  Ann.  Kept.,  pt.  3,  p.  478. 
Pentacrinus  asteriscus  Stanton,  1899,  U.  S.  Geol.  Survey  Mon.,  vol.  32,  pt.  2,  p.  608. 
Pentacrinus  asteriscus  Knight,  1900,  Wyoming  Exper.  Sta.  Bull.  45,  PI.  IV,  fig.  2. 
Pentacrinus  askriscus  Darton,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Kept.,  pt.  4,  p.  521. 

Determinative  characters. — Columns  composed  of  medium-sized  pentagonal  joints  with 
moderately  deep  reentering  angles;  crenulated  ridge  of  suture  strongly  petaloidal;  column  per- 
forated by  canal  of  medium  size. 

Dimensions. — Column:  Diameter  of  joint  2  to  5  millimeters. 

Description. — First  described  by  Meek  and  Hayden  from  several  column  joints  found  in  the 
Black  Hills.  When  they  redescribed  and  figured  the  species  in  1865  they  combined  with- the 
earHer  forms  certain  smaller  column  joints  found  at  Red  Buttes  on  North  Platte  River,  figures 
of  which  were  given  in  the  text,  but  these  have  been  recently  doubtfully  referred  by  Springer  to 
Isocrinus  knighti.  Meek  and  Hayden  in  this  later  pubHcation  state  that  their  "description 
appUes  more  particularly  to  the  largest-sized  specimens"  from  the  Black  Hills  and  that  the  two 
figures  on  their  Plate  III  represent  these  forms,  which  must  therefore  be  regarded  as  the  type 
of  the  species. 

Many  similar  isolated  column  joints  have  been  found  widely  scattered  throughout  the 
Rocky  Mountain  region  by  different  geologists  and  most  of  them  are  regarded  by  the  author  as 
belonging  to  this  species.  Since  it  has  been  clearly  demonstrated  that  the  column  joints  vary 
in  the  different  portions  of  the  stem  of  nearly  all  crinoids  it  is  evident  that  several  different 
species  and  possibly  even  different  genera  may  be  represented  among  these  forms. 

The  specimens  referred  to  this  species  are  of  moderate  size,  clearly  pentagonal,  and  with 
moderately  deep  reentering  angles,  the  points  of  the  rays  being  sharp,  and  the  suture  joints 
apparently  uniting  to  form  a  compact  column. 

Hall  and  Whitfield  referred  doubtfully  to  Pentacrinites  asteriscus  Meek  and  Hayden  certain 
specimens  collected  by  Hayden  in  Nevada  from  "Hmestones  of  supposed  Triassic  age."  There 
is  much  doubt  as  to  this  form,  but  it  evidently  does  not  belong  to  P.  asteriscus. 

Related  forms. — The  species  presents  some  points  of  difference  from  P.  whitei,  which  has 
been  generally  regarded  as  belonging  to  it.  Its  column  joints  are  generally  somewhat  smaller, 
are  not  alternating,  do  not  have  as  deep  reentering  angles,  and  its  rays  ai-e  somewhat  sharper. 
The  crenulation  of  its  petaloid  area  is  also  somewhat  different.  This  species  is  somewhat  similar 
to  Pentacrinus  shastensis  of  the  Pacific  coast,  but  the  latter  is  of  slightly  different  form  and  gen- 
erally has  shallower  reentering  angles. 

Localities. — South  and  southwest  base  of  Black  Hills,  South  Dakota  (type),  and  Red  Buttes, 
Wyo. ;  South  Dakota,  Idaho,  and  Colorado  (Meek) ;  southeastern  Idaho  and  western  Wyoming 
(Peale);  Black  Hills,  South  Dakota  (Whitfield);  Sundance  formation  (Upper  Jurassic),  Black 
HiUs,  South  Dakota  (Darton). 

Geologic  horizon. — Jurassic. 

Collection. — U.  S.  National  Museum  (220) ;  University  of  Kansas. 

Pentacrinus  whitei  Clark. 

Plate  III,  figures  3a-c. 

Pentacrinus  asteriscus  Wiite,  1875,  U.  S.  Geog.  Surveys  W.  100th  Mer.  Kept.,  vol.  4,  pt.  1,  p.  162,  PI.  XIII,  figs.  6a-b. 
Pentacrinus  whitei  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Pentacrinus  whitei  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  27,  28,  PI.  Ill,  figs.  2a-d. 
Pentacrinus  ivhitei  Springer,  1909,  U.  S.  Nat.  Mus.  Proc,  vol.  36,  p.  188. 

Determinative  bharacters. — Column  composed  of  large,  thin,  alternating,  pentagonal  joints 
with  deep  reentering  angles;  crenulated  ridges  of  suture  with  strong  pentaloid  arrangement; 
column  perforated  by  canal  of  medium  size. 


28  MESOZOIC    AND   CENOZOIC   ECHINODEBMATA   OF    THE   UNITED    STATES. 

Dimensions. — Column:  Diameter  of  joint  5  to  8  millimeters;  height  of  joint  ]  to  H 
milUmetei-s. 

Description. — C.  A.  White  describes  and  figures  certain  specimens  as  Pentacrinus  asteriscus 
Meek  and  Hayden  that  evidently  belong  to  a  different  species.  Springer,  who  has  examined  the 
same  material,  is  likewise  of  the  opinion  that  the  separation  of  the  foi-ms  from  P.  asteriscus  is 
well  fomided.  The  name  P.  wJiitei  was  proposed  by  the  author  in  honor  of  the  distinguished 
geologist  who  did  so  much  to  advance  our  knowledge  of  western  Amierican  Mesozoic  geology  and 
paleontology. 

The  column  joints  are  relatively  thin,  with  rounded  edges,  and  alternate  with  each  other,  so 
that  the  coliunn  does  not  appear  compactly  formed  when  viewed  from  the  side.  A  distinct 
petaloid  arrangement  of  the  crenulated  ridge  is  exliibited  in  all  the  forms. 

Related  forms. — The  species  is  apparently  closely  related  to  P.  asteriscus,  from  which  it  is 
separated  by  its  generally  larger  alternating  joints,  deeper  reentering  angles,  and  less  compact 
column. 

Localities. — Salt  Creek  (type)  and  Diamond  Valley,  Utah  (White). 

Geologic  horizon. — Jurassic. 

Collection. — U.  S.  National  Museum  (8588) . 

Pentacrinus  shastensis  Clark,  n.  sp. 

Plate  III,  figure  4. 

Determinative  characters. — Column  composed  of  rather  large  pentagonal  joints,  with  promi- 
nent reentering  angles.  The  crenulated  ridges  of  the  suture  have  a  rounded  petaloid  arrange- 
ment.    Column  perforated  by  a  rather  large  canal. 

Dimensions. — Column:  Diameter  of  joint  6  to  9  millimeters;  thickness  of  joint  1  to  IJ  milli- 
meters. 

Description. — A  number  of  casts  of  column  joints  of  a  Pentacrinus  of  medium  size  have  been 
found  in  a  very  compact  sandstone.  They  show  very  clearly  the  shape  and  exterior  markings 
of  the  joints,  which  have  very  pronounced  reentermg  angles  and  sharp  long  rays.  In  one  of  the 
best  preserved  specimens  the  crenulated  edges  of  the  suture  present  a  prominent  petaloid  arrange- 
ment. This  is  not  distinguishable  in  most  of  the  specimeiis,  which  are  too  poorly  preserved  to 
show  the  finer  details.  Two  of  the  specimens  are  casts  of  several  combined  joints  in  which  the 
side  characters  of  the  column  are  clearly  shown.  The  column  is  perforated  by  a  rather  large 
canal. 

Belated  forms. — The  species  is  somewhat  similar  to  P.  asteriscus  Meek  and  Hayden,  but  is 
larger  and  of  somewhat  different  form. 

Localities. — One-haK  mile  north  of  Holcombs  stage  station,  4  miles  north  of  Buzzards  Roost, 
and  about  2^  miles  west  of  Buzzards  Eoost  (type),  Shasta  County,  Cal. 

Geologic  horizon. — Jurassic. 

Collection.— U.  S.  National  Museum  (31190). 

Class  STELLEROIDEA. 
Subclass  ASTEROIDEA. 
Order  CRYPTOZONIA. 

Family  ASTERIIDiE. 

Genus  ASTEBIAS  lirmseus. 

AsTERiAs?  DUBiuM  Whitfield. 
Plate  III,  figure  6. 

Asterias^  dubium  Whitfield,  1877,  Preliminary  report  on  the  paleontology  of  the  Black  Hills,  p.  15. 
Asterias'!  dubium  Wliitfield,  1880,  Paleontology  of  the  Black  Hills  of  Dakota,  pp.  344,  345,  PI.  Ill,  fig.  3. 
Asterias  dubium  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Asterias?  dubium  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  31,  32,  PI.  V,  fig.  2. 
Asterias  dubium  Logan,  1900,  Kansas  Univ.  Quart.,  vol.  9,  pp.  130,  131,  PI.  XXV,  fig.  4. 


JUKASSIC   ECHINODEEMATA.  29 

Determinative  characters. — Imperfectly  preserved  forms  of  small  size,  with  slender  flexuous 
arms,  apparently  covered  superiorly  with  longitudinal  rows  of  plates. 

Dimensions.—  Diameter  of  disk  10  to  12  millimeters;  length  of  arms  15  to  28  milluneters. 
Description. — This  interesting  but  doubtful  form  is  thus  characterized  by  Whitfield: 

The  specimens  are  not  in  condition  to  afford  a  full  description  of  their  specific  characters.  They  are  of  small  size, 
the  rays  being  from  three-fourths  of  an  inch  to  IJ  inches  long,  measuring  from  the  center  of  the  body.  The  rays  are 
slender  and  flexuous,  most  of  them  being  more  or  less  curved  in  their  direction  and  elevated  along  the  middle,  as  shown 
on  a  gutta-percha  cast  taken  in  a  natural  mold  of  a  group  of  three  individuals.  The  upper  surface  is  subangular,  and  in 
structure  they  are  apparently  composed  of  small  uniform  plates,  placed  in  longitudinal  rows.  The  center  of  the  body 
or  disk  is  marked  by  an  obscurely  pentangular  depression  on  the  upper  surface.  None  of  the  specimens  show  the  under 
side  of  the  body  or  rays,  so  that  the  characters  of  these  parts  are  entirely  unknown. 

The  species  appears  to  have  Iseen  somewhat  abundant,  judging  from  the  condition  in  which  tliey  are  grouped  on 
the  sandstone,  and,  although  the  specimens  are  obscure  and  too  imperfect  for  positive  determination  and  description 
it  has  been  thought  best  to  designate  them  by  names,  as  they  will  undoulitedly  prove  a  characteristic  form  over  a  cer- 
tain region  and  of  a  limited  horizon.  The  sandstone  is  marked  by  the  layers  in  which  they  are  found  Ijy  ripple  or  wave 
marks,  having  a  width  of  about  3  inches,  and  indicates  a  near  proximity  to  a  shore  line  over  the  area  where  they  were 
obtained ,  and  that  the  indi\dduals  are  probaljly  stranded  specimens.  A  single  very  imperfect  impression  of  a  lamelli- 
branchiate  shell  is  seen  on  the  same  fragments  of  rock,  but  too  imperfect  for  determination. 

Related  forms. — This  doubtful  species  scarcely  admits  of  comparison  with  other  forms. 
There  is  nothing  from  American  Jurassic  strata  with  which  it  can  be  closely  associated. 

Localities. — East  side  of  Spearfish  Creek  near  its  junction  mth  the  Redwator,  Black  Hills, 
South  Dakota  (tjiio);  Freezeout  Hills,  Wyoming  (Logan). 

Geologic  horizon. — In  red  sandstones  of  Jurassic  age  70  feet  above  the  "  Red  Bods  "  (Wliitfield 
type) ;  in  a  thin  stratum  of  sandstone  in  the  Jurassic  bluish  shale,  No.  15  of  the  section  (Loo-an) 
Jurassic. 

Collections. — U.  S.  National  Museum  (325);  Kansas  University  Museum. 

Subclass  OPHIUROIDEA. 
Order  ZYGOPHIURJE. 
Family  OPHIOLEPIDID^. 

Genus  OPHIOGLYPHA  liyman. 

Ophiogltpha  utahensis  Clark,  n.  sp. 

Plate  III,  figure  5. 

Determinative  characters. — Dorsal  or  aboral  surface  of  disk  composed  of  numerous  small 
imbricating  plates  wAth  five  pairs  of  "ratlial  shields."  Doi-sal  arm  plates  vnihv  than  high  near 
the  disk,  gradually  becoming  longer  toward  the  extremity  of  the  arms.  Narrow  lateral  arm 
plates  shown  on  several  of  the  arms. 

Dimensions. — Diameter  of  disk  8  millimeters;  length  of  arm  10  millimeters  (not  entire)- 
width  of  arm  near  disk  \\  milUmeters. 

Description. — The  only  specimen  of  this  species  contains  two  individuals  on  the  same  slab 
together  with  a  few  fragments  of  arm  plates.  The  aboral  surface  of  the  disk  of  one  indivitlual 
and  several  of  the  arms  are  in  a  good  state  of  preservation.  Th^  surface  of  the  disk  is  covered 
with  a  very  large  number  of  nearly  equal  sized  imbricating  plates  of  rounded  form  with  the  excep- 
tion of  the  "radial  shi.4ds,"  which  are  larger  and  elongate  and  stand  in  pairs  at  tho  head  of  the 
arms.  The  arms  are  long,  but  all  the  outer  extremities  are  broken,  so  that  the  full  length  can  not 
be  determined.  The  dorsal  arm  plates  are  wider  than  high  near  the  disk,  but  gradually  lengthen 
as  the  distance  from  the  disk  increases  until  they  become  longer  than  wide.  The  lateral  arm 
plates  are  preserved  in  places  and  appear  as  narrow  plates  more  or  less  detached  from  the  arms. 
The  spines  are  not  clearly  shown. 

Locality. — San  Rafael  River  10  miles  below  Castledale,  Utah. 

Geologic  horizon. — Jurassic. 

Collection. — U.  S.  National  Museum  (22839). 
39800°— 15 3 


30  MESOZOIC   AND  CENOZOIC   ECHINODEEMATA   OF   THE   UNITED   STATES. 

Class  ECHINOIDEA. 

Subclass  REGUT.ARIA  ENDOBRANCHIATA. 
Order  CIDAROIDEA. 

Family  CIDARIDjE. 

Genus  CIDARIS  Leske. 

CiDARis  CALiFOENicus  Clark. 

Plate  IV,  figures  la-c. 

Cidaris  calif ornicus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Cidaris  califomicus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  36,  PI.  VI,  figs.  la-b. 

Determinative  characters. — Test  unknown.  Spines  large,  club-shaped,  with  rows  of  large 
granules  that  coalesce  to  form  longitudiaal  ridges  which  extend  from  neck  to  pomt  of  spine. 

Dimensions. — Largest  spine:  Length  22  millimeters;  breadth  in  thickest  part  5  millimeters. 

Description. — This  species  is  based  on  detached  spines,  four  or  five  specimens  of  which  are 
found  in  material  from  Taylorsville,  Cal.  They  are  distinctive  in  every  way  and  can  not  be 
mistaken,  even  in  fragments.  The  specimens  examined  are  casts  but  are  so  well  preserved  that 
impressions  in  gutta-percha,  from  which  the  drawings  were  made,  show  the  characters  com- 
pletely. Each  spme  has  a  short  narrow  neck,  beyond  which  it  rapidly  increases  in  size  so  as  to 
give  a  club-shaped  outhne  to  the  middle  and  upper  portions.  Rows  of  longitudinal  granules 
cover  the  surface  from  the  neck  to  the  point  of  the  spine,  presenting  the  appearance  of  long 
serrated  ridges. 

Related  forms. — Separated  from  C.  taylorensis  by  its  club-shaped  form  and  surface  char- 
acters. 

Locality. — TaylorsviUe,  Plumas  County,  Cal. 

Geologic  horizon. — Mormon  sandstone.  Middle  Jurassic. 

Collection, — U.  S.  National  Museum  (.30184). 

Cidaris  taylorensis  Clark. 

Plate  IV,  figures  2a-b. 

Cidaris  taylorensis  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Cidaris  taylorensis  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  35,  PL  VI,  figs.  2a-b. 

Determinative  characters. — Test  small.  Interambulacra  wide.  Tubercles  large,  with  cir- 
cular areolas,  much  depressed  marginally;  boss  crenulated;  mamelon  perforated.  Miliary 
space  narrow.  Spines  long,  cylindrical,  covered  with  small  granules  arranged  in  longitudinal 
rows. 

Dimensions. — Test  small  but  undetermined.  Largest  spine:  Length  30  millimeters  (?); 
width  in  broadest  portion  5  millimeters. 

Description. — The  fragments  of  this  form,  although  they  permit  determmation  of  but  few  of 
the  important  characters,  warrant  specific  description  from  the  fact  that  they  are  totally  distinct 
from  the  only  other  representative  of  Cidaris  from  the  Jurassic  rocks  of  America.  The  small 
fragments  of  the  interambulacrum  and  the  spine  occur  together  and  doubtless  formed  part 
of  the  same  individual.  The  interambulacral  plates,  of  which  only  portions  are  preserved 
on  the  specimen  figured,  indicate  a  form  of  no  great  size.  The  tubercles  are  large,  with  depressed 
areolas  surrounded  by  a  circle  of  large  granules.  The  boss  is  crenulated  and  the  mamelon  per- 
forated. The  miliary  space  is  apparently  narrow,  the  tubercles  of  adjacent  plates  in  the  same 
column  bemg  nearly  confluent. 

The  spine  is  long,  gently  tapering  toward  the  base  in  the  portion  preserved,  and  covered 
with  longitudinal  rows  of  small  granules. 

Related  forms. — As  the  Jurassic  strata  of  North  America  afford  few  fossil  Echmodermata  as 
compared  with  the  Cretaceous,  there  are  not  many  American  types  with  which  the  present  form 


JUEASSIC   ECHINODEKMATA.  31 

may  be  compared.  C.  californicus  is  not  known  by  its  test  and  comparisons  are  limited  to  the 
spines.  In  C.  taylorensis  the  spines  are  long  and  cylindrical,  while  in  C.  californicus  they  are 
short  and  thick  set,  and  have  a  totally  different  surface  decoration.  C.  taylorensis  differs  from 
C.  flumasensis  in  its  smaller  miliary  space  and  ch'cular  aroolas. 

Locality. — TaylorsviUe,  Plumas  County,  Cal. 

Geologic  horizon. — Hardgrave  sandstone.  Lower  Jurassic. 

Collection. —V.  S.  National  Museum  (.30183). 

CiDARis  PLUMASENSis  Clark,  n.  sp. 
Plate  IV,  figure  3. 

Determinative  characters. — Test  medium  size.  Ambulacra  narrow.  Interambulacra  wide. 
Tubercles  large  with  oval  depressed  areolas,  crenulated  boss,  and  perforated  mamelon.  Miliary 
space  covered  with  coarse  granules. 

Dimensions. — Height  of  largest  ambulacral  plate  10  millimeters ;  width  14  miUhneters. 

Description. — Fragments  of  casts  of  the  test  of  this  species  are  fovmd  on  a  single  slab  of 
sandstone.  The  most  perfect  unpression  is  of  three  interambulacral  plates  with  adjacent  ambu- 
lacral plates.  It  is  evidently  part  of  the  test  of  a  form  of  medium  size.  The  ambulacra  are 
narrow  but  the  impression  of  the  plates  is  obscure.  The  interambulacral  plates  are  much  better 
preserved  and  show  large  tubercles  with  oval  areolas,  somewhat  depressed.  The  boss  is  crenu- 
lated and  the  mamelon  perforated.  The  miliary  space  is  rather  wide  and  is  covered  with  coarse 
granules. 

Locality. — TaylorsviUe,  Plumas  County,  Cal. 

Geologic  horizon. — Hardgrave  sandstone.  Lower  Jurassic. 

Collection.— V.  S.  National  Museum  (31191). 

Subclass  REGULARIA  ECTOBRANCHIATA. 

Order  DIADBMOIBEA. 

Suborder  ARBACINA. 

FamUy  HEMICIDARID^. 

Genus  HEMICIDARIS  Agassiz. 

Hemicidaris  intumescens  Clark. 

Plate  IV,  figures  4a-i. 

Hemicidaris  intumescens  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Hemicidaris  intumescens  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  44,  45,  PI.  XII,  figs.  la-i. 

Determinative  characters. — Test  spheroidal,  upper  surface  inflated,  lower  surface  flat.  Am- 
bulacra moderately  broad,  increasing  in  width  from  the  apical  system  to  the  peristome.  The 
tubercles  at  the  peristome  are  nearly  equal  m  size  to  those  of  the  interambulacral  areas,  but 
become  greatly  reduced  in  passing  from  the  ambitus  to  the  apical  system.  Interambulacra 
rather  wide,  with  two  rows  of  large  tubercles.  Miliary  space  wide,  covered  with  numerous 
granules.     Peristome  moderately  wide,  with  deep  incisions. 

Dimensions. — Diameter  18  millimeters;  height  12  millimeters. 

Description. — The  very  perfectly  preserved  molds  of  the  species  permit  the  taking  in  gutta- 
percha of  all  the  details  of  form  and  structure.  As  the  only  re])resentative  of  the  genus  in 
American  deposits  it  possesses  considerable  interest.  The  test  is  of  moderate  size,  with  a  con- 
vex and  shghtly  inflated  upper  surface  and  nearly  flat  lower  surface.  The  slightly  flexuous 
ambulacra  broaden  from  the  region  of  the  apical  disk  toward  the  ambitus  aiid  slightly  contract 
again  before  the  peristome  is  reached.  The  tubercles  are  prominent  in  the  lower  part  of  the 
column,  where  several  pairs  attain  a  size  nearly  equal  to  those  of  the  interambulacra.  Minute 
perforated  granules  succeed  them  above  and  continue  as  a  double  row  to  the  apical  system.     The 


32  MESOZOIC    AND    CENOZOIC   ECHINODEKMATA    OF    THE    UNITED    STATES. 

poriferous  zones  are  slightly  flexuous,  ami  the  small  pores  are  uniserially  arranged,  although 
somewhat  increased  in  the  vicinity  of  the  peristome. 

The  interambulacra  are  three  to  four  times  the  width  of  the  ambulacra  at  the  ambitus.  The 
two  rows  of  medium-sized  tubercles  occupy  the  center  of  the  plates;  the  areola  is  circular  and 
shghtty  elevated;  the  boss  deeply  crenulated,  and  the  mamelon  distinctty  perforated.  There 
are  about  eight  primary  tubercles  in  each  row.  The  apical  system  is  rather  large,  although  not 
sufhciently  well  jjreserved  to  admit  of  a  determination  of  the  individual  plates. 

The  peristome  is  small  and  occupies  scarcely  one-half  of  the  diameter  of  the  test.  It  is 
deeply  notched,  the  lobes  being  nearly  equal  in  size. 

Related  forms. — The  present  species  of  Hemicidaris  is  the  only  representative  of  the  genus 
known  from  American  deposits.  A  comparison  with  European  species  fails  to  identify  it  with 
any  described  form. 

Locality. — Taylorsville,  Plumas  County,  Cal. 

Geolocfic  liorizon. — Mormon  sandstone,  Middle  Jurassic. 

Collection. ^U.  S.  National  Museum  (.30187  and  30188). 

Suborder  DIADEMINA. 
Family  DIADEMATIDiE. 

Genus  PSEUDODIADEMA  Desor. 
PSEUDODIADEMA    EMERSONI    Clark. 

Plate  V,  figures  la-e. 
Pseudodiadeinaemersoni  Clark,  189.3,  U.  S.  Geol.  Survey  Bull.  97,  pp.  45,  46,  PI.  XII,  figs.  2a-e. 

Determinative  characters. — Test  circular,  depressed.  Ambulacra ' straight  and  prominent; 
poriferous  zones  narrow;  pores  uniserial.  Interambulacra  not  quite  twice  the  width  of  the 
ambulacra  with  two  rows  of  large  tubercles,  eight  or  nine  in  each  row.     Peristome  wide. 

Dimensions. — Diameter  15  millimeters;  height  7  millimeters. 

Description. — The  beautiful^  preserved  molds  of  this  interesting  form  were  collected  by 
Hyatt  from  the  Jurassic  beds  of  Taylorsville,  Cal.  The  gutta-percha  casts  from  which  the  draw- 
ings were  made  represent  very  perfectly  all  the  details  of  structure.  The  test  is  nearly  circular, 
the  prominent  ambulacra  are  rather  more  than  one-half  the  width  of  the  interambulacra,  and 
support  two  rows  of  primary  tubercles  somewhat  smaller  than  the  interambulacral  tubercles. 
There  are  nine  or  ten  in  each  row.  Between  the  tubercles  are  numerous  granules  that  are 
arranged  in  an  undulating  Hne  between  the  rows  and  along  the  margin.  They  nearly  disappear 
between  the  tubercles  of  the  same  scries.  Toward  the  apical  system  the  tubercles  are  greatly 
reduced  in  size.  The  pores  are  uniserial,  there  being  three  or  four  opposite  each  ambulacral 
plate. 

The  interambulacra  bear  two  rows  of  primary  tubercles,  eight  or  nine  in  each,  that  are  only 
slightly  larger  than  those  of  the  ambulacral  areas.  They  increase  from  the  peristome  to  the 
ambitus,  after  which  they  rapidly  decrease  in  size.  The  areolas  are  nearly  confluent  above  and 
below,  broader  than  long,  and  rise  into  prominent  bosses  that  are  not  dee])ty  crenulated.  The 
mamelon  is  distinctly  perforated.  The  miliary  space  is  covered  with  granules  of  different  sizes. 
There  are  no  secondary  tubercles  developed  near  the  peristome.  The  lower  surface  is  flat,  the 
peristome  large  and  deeply  notched ;  the  ambulacral  lobes  larger  than  the  interambulacral.  The 
apical  system  is  not  preserved.  This  species  is  named  in  honor  of  B.  K.  Emerson,  of  Amherst 
CoUege,  from  whom  the  writer  received  his  first  instruction  in  geology  and  ])aleontology. 

Related  forms. — The  species  is  unique,  l)eing  the  only  Pseudotliadema  in  the  Jurassic  of 
America  and  being  only  veiy  doubtfully  identical  with  any  European  form.  It  resembles  P. 
baileyi  from  England  in  many  particulars  but  is  less  depressed,  has  more  rounded  sides,  and  more 
numerous  granules  in  the  miliary  space. 

Locality. — Taylorsville,  Plumas  County,  Cal. 

Geologic  horizon. — Mormon  sandstone,  Middle  Jurassic. 

Collection. — U.  S.  National  Museum  (30186). 


JURASSIC   ECHINODERMATA.  33 

Family  PEDINIDvE. 

Genus  STOMECHINUS  Desor. 

Stomechinus  hyatti  Clark. 

Plate  V,  figures  2a-e. 

Stomechinus  hyatti  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Stomechinus  hyatti  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  56,  PI.  XXIII,  figs.  la-e. 

Determinative  characters. — Test  high,  circumference  circular.  Ambulacra  with  four  rows 
of  small  primary  tubercles;  poriferous  zones  ^vide,  triserial.  Interambulacra  with  eight  or  ten 
rows  of  tubercles  that  diniinish  in  number  toward  apical  sj'stem  and  peristome,  with  a  depression 
along  the  line  of  the  central  suture. 

Dimensions. — Diameter  25  millimeters;  height  25  millimeters. 

Description. — Only  the  cast  of  a  portion  of  the  exterior  of  a  single  specimen  of  this  interest- 
ing Jurassic  form  is  jireserved.  The  test  is  high,  and  the  circumference  circular  or  sUghtly  sub- 
pentagonal.     The  sides  rise  abruptly  from  the  margin. 

The  ambulacra  are  about  one-half  the  width  of  the  interambulacra  and  preserve  a  nearly 
uniform  width  throughout.  There  are  four  rows  of  tubercles  that  increase  gradually  in  size 
from  above  downward.  A  depression  appears  along  the  hne  of  the  central  suture.  The  porif- 
erous zones  are  wide;  the  pore  pairs  are  placed  in  obUque  ranks  of  three,  and  each  rank  is 
separated  from  that  next  to  it  by  two  small  tubercles. 

The  interambulacra  are  about  twice  the  width  of  the  ambulacra  and  the  plates  of  the  former 
are  but  sUghtly  higher  than  those  of  the  latter.  Each  plate  is  covered  at  the  widest  part  of  the 
area  with  an  irregular  row  of  four  or  five  tubercles  that  are  of  about  the  same  size  as  those  of  the 
ambulacra.  The  tubercles  are  uncrenulated  and  imperforate.  A  wide  depression  extends 
along  the  medial  Une  of  each  interambulacral  area,  according  with  the  position  of  the  central 
suture. 

The  regions  of  the  apical  disk  and  peristome  are  largely  wanting,  but  a  deep  incision  sho^vn 
upon  the  margin  of  the  latter  indicates  that  it  is  distinctly  lobed  throughout. 

Related  forms. — The  American  species  shows  some  points  of  identity  with  StomecJiinus  nudus 
Wright  of  England  but  is  more  elevated,  has  a  less  sharp  marginal  angle,  and  has  a  more  regular 
arrangement  of  the  tubercles. 

Locality. — Taylorsville,  Plumas  County,  Cal.  . 

Geologic  horizon. — iformon  sandstone,  Middle  Jurassic.  .     /i 

Collection.— U.  S.  National  Museum  (30185).  j 

Subclass  IRREGULARIA. 

Order  GNATHOSTOMATA. 

Suborder  HOLECTYPINA. 

Family  PYGASTERID.E. 

Genus  HOLECTYPUS  Desor. 

HoLECTYPUs  PEALEi  Clark,  n.  sp. 

Plate  V,  figures  3a-b. 

Determinative  characters. — Test  subcircular,  subcorneal.  Ambulacra  rather  narrow,  nearly 
straight;  poriferous  zones  distinct.  Interambulacra  prominent  with  large  plates.  Apical  system 
imperfect. 

Dimensions. — Diameter  15  to  25  millimeters;  height  10  to  15  millimeters. 

Description. — Several  casts  of  a  typical  Holectypus  from  the  Jurassic  beds  of  Yellowstone 
River  were  collected  by  Peale  in  Montana  many  j^ears  ago  but  were  never  described.  More 
recently  a  still  more  perfect  specimen  was  obtained  by  W.  H.  Weed  from  the  Yellowstone 
National  Park,  and  this  is  made  the  type  of  the  species.  The  specimens  .show  the  characteristic 
features  of  both  the  ambulacra  and  interambulacra,  but  the  adoral  and  aboral  regions  are  poorly 
preserved,  as  a  result  of  which  the  characters  of  the  apical  system,  peristome  and  periproct  are 


34  .     MESOZOIC   AND   CENOZOIC    ECHINODERMATA   OF    THE   UNITED    STATES. 

unknown.  The  ambulacra  are  very  distinct,  the  poriferous  zones  showing  clearly.  The  ambu- 
lacra are  narrow,  increasing  in  wdth  gradually'  to  the  ambitus.  The  interambulacra  stand  out 
prominently,  the  sutures  between  the  plates  being  clearly  indicated. 

Locality. — North  of  Berry  Creek,  Yellowstone  National  Park,  Wyo. 

Geologic  'h.orizo7i. — Jurassic. 

Collection. — U.  S.  National  Museum  (31192). 

HoLECTYPUS  CRAGiNi  Clark,  n.  sp. 
Plate  V,  figure  4. 
Holectypus  ?  sp.  Cragin,  1905,  U.  S.  Geol.  Survey  Bull.  266,  p.  35. 

Determinative  characters. — Test  subcircular,  subconical.  Ambulacra  narrow,  straight,  with 
several  rows  of  tubei'cles ;  poriferous  zones  straight  and  narrow.  Interambulacra  wide.  Apical 
system  imperfect. 

Dimensions. — Diameter  28  milUmeters;  height  15  nulhmeters. 

Description. — ^The  fragmentary  specimen  referred  to  by  Cragin  is  an  unquestioned  Holec- 
typus and  presents  many  of  the  diagnostic  characters  of  that  genus.  It  is  not  unhke  H.  plariatxis 
in  general  outhne,  but  its  much  earher  geologic  position  renders  it  necessary  to  place  it  in  an  iiide- 
jjendent  species.  The  test  is  much  damaged,  so  that  its  essential  specific  characters  can  not  be 
determined.  The  outlines  of  the  ambulacra  and  interambulacra  can  be  seen,  but  the  individual 
plates  are  mth  cUfhculty  distinguished.  The  ambitus  is  relativelj'  sharp,  indicating  a  flat  under- 
surface.  The  tubercles  in  this  species  are  evidently  small  and  cover  the  greater  portion  of  the 
plates.     The  apical  sj^stem  is  small  but  the  individual  plates  can  not  be  distinguished. 

Belated  forms. — ^This  species  is  wholly  unhke  H.  peaJi  in  form  and  is  evidently  a  chfferent 
species. 

Locality. — Malone  Mountain,  Texas. 

Geologic  liorizon. — Malone  formation.  Upper  Jurassic. 

Collection.— \] .  S.  National  Museum  (31193). 

Order  ATELOSTOMATA. 

Suborder  ASTERNATA. 

Family  CASSIDULID^. 

Genus  PYGTTBTJS  Agassiz. 

Pygukus  sp. 

Pygurus  sp.  Cragin,  1905,  U.  S.  Geol.  Survey  Bull.  266,  p.  36. 

Description. — Cragin  describes  the  form  as  foUows: 

Among  the  specimens  submitted  by  Dr.  Stanton  is  a  fragment  of  the  test  of  a  sea  urchin  of  the  genus  Pygurus.  It 
includes  the  main  part  of  the  aboral  half  of  an  ambulacrum.  The  genus  is  clearly  determined  by  the  form  of  the 
ambulacrum  and  the  form  and  arrangement  of  the  pores,  as  well  as  by  the  character  of  the  tubercles  and  by  the  dis- 
coidal  form  of  the  test,  the  latter  form  being  indicated  by  the  flatness  of  the  part  preserved.  The  ambulacrum  has  the 
biconcave  outline  that  characterizes  the  upper  part  of  that  of  Pygurus.  The  pores  of  the  outer  row  are  very  long  and 
slitlike,  widened  slightly  toward  the  outer  end,  and  subhorizontal  to  more  or  less  oblique;  those  of  the  inner  row  more 
ringent,  compressed  dotlike  or  hyphen-like,  and  oblique,  their  width  being  considerably  less  and  their  length  consid- 
erably more  than  that  of  any  of  the  circumtubercular  courts  on  the  neighboring  part  of  the  ambulacrum.  The  ambu- 
lacral  plates  are  exceedingly  narrow;  the  imperforate  part  of  each,  in  the  widest  part  of  the  ambulacrum,  being  about 
10  times  as  long  (transverse)  as  wide  (parallel  to  the  course  of  the  ambulacrum)  and  ornamented  ^vith  1  to  3  small 
perforated  tubercles,  each  of  which  is  set  in  a  round,  depressed  court.  The  distinction  of  these  tubercles  is  irregular, 
but  they  are  so  few  and  so  feebly  developed  on  the  inner  ends  of  the  plates  as  to  give  the  ambulacrum  the  aspect  of 
ha\-ing  a  median  plain  zone,  to  which  the  seams  between  the  plates  give  a  transversely  striated  appearance. 

Measurements. — Maximum  width  of  ambulacrum  16,  of  which  the  two  pore  belts  each  occupy  3.5  and  the  imper- 
forate tract  9  millimeters;  length  and  width  of  each  imperforate  part  of  an  ambulacral  plate  in  broadest  part  of  the 
ambulacrum,  respectively,  4.5  and  0.43  millimeters;  length  of  outer  slitlike  pores  in  broadest  part  of  ambulacrum  2 
millimeters,  which  is  about  one-fourth  of  the  width  of  a  semiambulacrum. 

Occurrence. —AVest  side  of  Malone  Mountain,  about  2  miles  southwest  of  Malone  station,  in  No.  25  of  Dr.  Stanton's 
Malone  Mountain  section;  with  Gryphxa  mexicana,  Pleuromya  ineonstans,  Pinna  quadrifrons,  etc. 

Geologic  h orizon . — Jurassic . 
Collection. — U.  S.  National  Museum. 


CRETACEOUS  ECHINODERMATA. 

Class  CRINOIDEA. 

Subclass  DICYCLICA. 

Order  INADTJNATA. 

Suborder  BENDROCRINOIDEA. 

Family  PENTACRINID^. 

Genus  PENTACRINUS  Bltimenbach. 

Pentacrinus  tehamaensis  Clark,  n.  sp. 

Plate  VI,  figure  1. 

Determinative  characters. — Column  composed  of  small  and  medium  sized  pentagonal  joints, 
some  with  and  some  without  sharp  reentei-ing  angles.  Crenulated  ridges  petaloid.  Column 
perforated  by  a  small  canal. 

Dimensions. — Column:  Diameter  of  joint  3  to  6  millimeters;  thickness  of  joint  J  to  1 
milhmeter. 

Description. — Numerous  isolated  fragments  of  Pentacrinus  columns  have  been  found  in 
the  California  Cretaceous.  The  larger  joints  are  of  medium  size.  Many  very  small  joints  are 
found  with  the  larger  ones  and  probably  belong  to  the  same  species.  The  crenulations  are  dis- 
tinct and  form  five  well-marked  petaloid  areas  on  the  upper  and  lower  surfaces  of  the  joints. 
The  column  is  perforated  by  a  small  central  canal. 

Localities. —Shelton's  ranch,  5  miles  north  of  Paskenta,  Tehama  County  (type),  and  Texas 
Springs,  Cal. 

Geologic  horizon. — Knoxville  formation,  Lower  Cretaceous,  and  beds  doubtfully  assigned  to 
the  lower  part  of  the  Chico  formation.  Upper  Cretaceous. 

Collection. — U.  S.  National  Museum  (31194). 

Pentacrinus  bkyani  Gabb. 

Plate  VI,  figures  2a-b. 

PentacrinushryaniGskib,  1876,  Acad.  Nat.  Sci.  Philadelpliia,  Proc,  vol.  28,  p.  178,  PL  V,  figs.  1,  la,  lb. 
Pentacrinus  hryani  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Pentacrinus  hryani  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  28,  29,  PI.  Ill,  figs.  3a-b. 
Pentacrinus  6n/am"  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  6. 

Pentacrinus  bryani  Weller,  1907,  Cretaceouspaleontologyof  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  276-277,  PI.  VI, 
figs.  8,  9. 

Determinative  characters. — Column  composed  of  moderately  large,  rather  thick,  pentagonal 
joints,  with  sharp  reentering  angles.  The  crenulated  ridges  are  broadly  petaloid  and  each  area 
is  rounded  at  its  outer  extremity.     Column  perforated  by  canal  of  medium  size. 

Dimensions. — Column:  Diameter  of  joint  6  millimeters;  thickness  of  joint  1  millimeter. 

Description. — Two  small  fragments  of  the  stem  of  this  form  were  described  by  Gabb  in  1876. 
As  the  first  representative  of  this  family  reported  from  the  American  Cretaceous  it  j^ossesses 
considerable  interest.  The  column  is  composed  of  moderately  large,  thick  joints,  that  reach 
about  6  millimeters  in  diameter  and  about  one-fifth  of  that  in  thickness.  The  broad,  rounded 
ridges  at  the  salient  angles  of  the  pentagonal  outhne  form  a  nearly  unbroken  line,  and  tlie  furrow 
at  the  reentering  angles  is  alternately  depressed  and  elevated  in  successive  joints.     The  edge 

35 


36  MESOZOIC    AND    CENOZOIC   ECHINODEEMATA   OF    THE    UNITED    STATES. 

of  each  jouit  is  slightly  rounded.  The  crenulated  surfaces  form  five  broad  petaloid  areas  dis- 
tinctly rounded  at  the  outer  extremities  and  unite  near  the  inner  edge  of  the  reentering  angles 
to  form  a  double  fiat-topped  ridge  that  reaches  to  the  central  canal,  around  which  there  is  like- 
wise a  slight  elevation.  The  crenulations  are  clearly  visible  on  the  outer  surface  of  the  column. 
The  column  is  perforated  b}''  a  central  canal  of  medium  size. 

Related  forms. — ^This  species  is  quite  unlike  other  species  of  American  Pentacrinidse  and  is 
distinguished  from  Pentacrinus  tehamaensis  Clark  of  the  Pacific  coast  by  its  deeper  reentering 
angles. 

Locality. — Vincentown,  N.  J. 

Geologic  Tiorizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collections. — ^Academy  of  Natural  Sciences  of  Philadelphia  (1458) ;  Johns  Hopkins  University. 

FamUy  UINTACRINIDiE. 

Genus  TJINTACBINTJS  GrinneU. 

UiNTACRiNUS  sociALis  GrinneU. 

Plate  VI,  figures  3a-h;  Plate  VII,  figures  la-c. 

Uintacrinus  socialis  GrinneU,  1876,  Am.  Jour.  Sci.,  3d  ser.,  vol.  12,  pp.  81-83,  PI.  IV,  figs.  l-2b. 

Uintaerinus  socialis  Meek,  1876,  U.  S.  Geol.  and  Geog.  Survey  Terr.  Bull.,  vol.  2,  No.  4,  pp.  375-378,  figs.  A-B. 

Uintacrinus  socialis  Clark.  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  21-24,  Pis.  I,  II. 

Uintacrinus  socialis  Williston  and  Hill,  1894,  Kansas  Univ.  Quart.,  vol.  3,  No.  1,  pp.  19-21  and  diagram. 

Uintacrinus  socialis  Bather,  1896,  Zool.  Sec.  London  Proc.  for  1895,  pp.  974-1004,  Pis.  LIV-LVI,  13  figs. 

Uintacrinus  socialis  Logan,  1898,  Kansas  Univ.  Geol.  Survey,  vol.  4,  pp.  481-483,  Pis.  XXI,  CXII. 

Uintacrinus  socialis  Beecher,  1900,  Am.  Jour.  Sci.,  4th  ser.,  vol.  9,  pp.  267-268,  Pis.  Ill,  IV. 

Uintacrinus  socialis  Springer,  1900,  Mus.  Comp.  Zool.  Mem.,  vol.  25,  No.  1,  pp.  1-89,  Pis.  I-VIII. 

Uintacrinus  socialis  Schuchert.  1904,  Smithsonian  Misc.  Coll.,  vol.  45,  p.  450,  PL  CIII. 

Uintacrinus  socialis  Bassler,  1909,  Smithsonian  Misc.  Coll.,  vol.  52,  pp.  267,  269,  Pis.  XVII,  XVIII. 

Determinative  cJiaracters. — Calyx  globose;  composed  of  very  thin,  usuaUj^  rather  fiat, 
although  sometimes  decidedly  convex  plates,  joined  together  by  a  very  loose  suture;  faces  at 
times  marked  by  faint,  irregular,  vertical  grooves.  Column  wanting.  Base  or  apical  system 
probably  dicyclic,  composed  of  centrale  surrounded  by  circlet  of  basals  (B)  or  circlet  of  infra- 
basals  (IB)  and  basals  (B)  as  the  case  may  be.  Encircling  the  base  and  alternating  with  the 
basals  are  five  abutting  radials  (R)  either  heptagonal  or  hexagonal  in  form.  Succeeding  the 
radials  are  two  primary  brachials  (IBr)  the  second  (IBr2)  axillary  and  generally  pentagonal  in 
form;  separatetl  by  interbrachials  (iBr)  which  may  vary  in  number  from  3  or  4  to  23.  Branch- 
ing from  the  axillary  brachial  are  the  secundibrachs  (IIBr)  or  distichals,  generally  the  first 
eight  of  which  are  fixed,  entering  into  the  composition  of  the  dorsal  cup.  Between  the  secundi- 
brachs are  intersecundibrachs  (illB)  or  the  interdistichals,  which  with  the  lower  pinnulars 
and  the  interpinnulars  of  all  areas  are  fixed.  The  normal  order  of  succession  of  pimiulars  is 
IIBr2  outer  TIBr4  inner  IIBrS  outer  IIBr7  imier  IIBrS  outer,  beyond  which  each  brachial  bears 
a  pinnule  on  alternate  sides  except  where  there  is  a  syzygy,  when  only  the  epizygal  is  pinnule- 
bearing.  Ventral  disk  or  tegmen  composed  of  plates  skin  covered  with  small  calcareous  plates 
or  spicules.  Mouth  excentric,  the  ambulacra  diverging  from  point  near  margin  of  disk.  Anus 
central,  large  and  conical. 

Dimensions. — Width  of  calyx  6.25  to  75  millimetei-s ;  medium-sized  specimen  40  milUmeters; 
length  of  arms  100  centimeters. 

Description. — The  writer  of  this  paper  gave  in  1893  a  more  extended  description  of  Vintcu- 
crinus  socialis  than  his  predecessors  had  done  and  was  able  for  the  first  time  to  show  the  struc- 
ture of  the  base,  which  was  fairly  well  preserved  on  a  smgle  specimen.  The  small  amount  of 
material  at  his  disposal  rendered  it  impossible  to  detect  some  important  structural  features 
observed  by  later  writers  who  had  access  to  more  abundant  and  better  preserved  specimens. 

S.  W.  Williston  and  B.H.Hill  described  better  specimens  of  Uintacrinus  socialis  iound  hj 
E.  E.  Schlosson  in  Logan  County,  Kans.     Williston  pointed  out  that  these  were  the  fii-st  speci- 


CRETACEOUS  ECHINODEKMATA.  37 

mens  found  in  place  and  unweathered.     He  says  that  the  long  arms  were  so  entangled  as  to  make 
it  very  difficult  to  trace  them  to  their  extremity. 

The  collection  by  H.  T.  Martin  of  a  large  number  of  specimens  of  Uintacrinus  socialis  from 
Williston's  locality  in  western  Kansas  furnished  several  museums,  among  them  the  British 
Museum  and  the  Peabody  Museum  of  Yale  University,  with  new  and  valuable  material.  The 
material  acquired  by  the  British  Museum  was  very  thoroughly  studied  in  1895  by  F.  A.  Bather, 
whose  morphologic  study  of  this  species  added  much  to  what  was  previously  known.  A  large 
slab  acquired  by  Yale  Univereity  was  described  by  C.  E.  Beecher  in  1900. 

The  complete  description  of  ZKntacrinus  socialis  and  the  true  interpretation  of  its  structm-e 
and  relations  were  not  made  until  1901,  when  Springer  obtained  from  western  Kansas,  through 
the  intelligent  collecting  of  H.  T.  Martin,  a  large  and  finely  preserved  lot  of  specimens,  far  more 
than  had  come  into  the  possession  of  any  of  his  predecessors.  With  his  wide  and  accurate  knowl- 
edge of  the  crinoids  he  has  been  able  to  add  more  than  any  of  his  predecessors  to  a  knowledge  of 
this  interesting  form  and  in  addition  to  the  discovery  of  dicyclic  as  well  as  monocycUc  individuals, 
was  also  able  to  find  a  number  of  specimens  with  well-preserved  tegmens  so  that  for  the  first 
time  a  knowledge  of  the  structm-e  of  the  ventral  surface  of  Uintacrinus  was  secured.  The  fol- 
lowing description  is  largely  based  on  Sprmger's  elaborate  discussion  of  this  form. 

The  calyx  is  globose  with  10  long  simple  arms  bearing  pinnules.  The  test  must  have  been 
flexible.  The  calyx  plates  are  thin,  frequently  convex  and  joined  together  by  loose  sutures,  the 
faces  of  which  are  at  times  slightly  grooved.  The  calyx  is  without  column  or  stalk  and  belongs 
to  the  class  of  free  forms. 

The  basis  is  composed  of  a  centrale,  sm-rounded  by  either  a  circlet  of  basals  or  a  circlet  of 
infrabasals,  which  are  in  turn  surrounded  by  the  basals.  The  centrale  in  the  first  form  has  its 
angles  radially  directed  and  in  the  second  interradially  directed.  The  form  is,  however,  proba- 
bly dicyclic.  The  infrabasal  circlet  is  not  complete  in  all  specimens,  some  havmg  only  4,  3,  2,  or 
even  1  infrabasals. 

The  radials  are  five  in  number  and  surround  the  basals,  with  which  they  alternate.  They  are 
equal,  six  or  seven -sided,  the  latter  occurring  where  the  edge  toward  the  basis  forms  a  reentrant 
angle.  The  radial  plates  are  wider  than  high  and  come  in  contact  with  one  another  only  in  the 
lower  portions  of  each  side.  They  come  in  contact  with  the  proximal  interbrachials  and  support 
the  fu'st  primibrachs. 

Following  the  radials  are  the  primibrachs,  secundibrachs  or  distichals,  and  fixed  pinnules, 
all  of  which  enter  into  the  formation  of  the  calyx,  to  which  are  added  interbrachials,  interdic- 
tichals,  and  interpinnulars.  It  is  not  always  easy  to  determine  the  exact  limits  of  marginal 
attachment  of  the  fixed  brachial  elements  in  the  fossil  state.  There  are  two  primibrachs,  the 
first  (IBrl)  hexagonal  in  form  abutting  on  the  radial  on  its  lower  margin,  and  the  second  primi- 
brach  (IBr2)  on  its  upper  margin  where  latterly  it  comes  into  contact  with  interbrachials  on  either 
side.  Both  the  firet  and  second  primibrachs  are  somewhat  narrower  than  the  radials.  The 
second  primibrach  is  axillary  and  generall}^  pentagonal  in  form.  It  also  abuts  on  interbra- 
chials on  either  side  and  beare  upoti  its  upper  margin  the  fu-st  of  the  secundibrachs. 

The  secundibrachs  or  distichals  are  commonly  fixed  in  the  first  eight  plates  with  the  aid  of 
the  fixed  pinnules,  interbrachials,  interdistichals,  and  interpinnulai-s.  Those  secundibrachs 
bearing  fixed  pinnules  appear  shghtly  axillary,  which  gives  the  appearance  of  a  somewhat  irregu- 
larly depressed  series. 

The  normal  order  of  succession  of  the  fLxed  pinnules  is  first  from  the  second  secundibrach  on 
the  outer  side,  the  next  from  the  fourth  secundibrach  on  the  inner  side,  then  from  the  fifth  secun- 
dibrach on  the  outer  side,  then  the  seventh  secundibrach  on  the  inner  side,  and  finally  from  the 
eighth  secundibrach  on  the  outer  side.  The  intervenmg  secundibrachs  do  not  bear  pinnules. 
Beyond  this  point  each  brachial  beare  generally  on  alternate  sides  a  pinnule  except  where  there 
is  a  syzygy  when  only  the  epizygal  beare  a  pinnule.  The  fixed  pinnules  comprise  fom-  or  five  to 
ten  of  the  proximal  plates.  The  number  of  plates  is  gi-eater  in  adults  than  in  the  young  forms. 
United  with  the  interbrachial  and  in  many  specimens  with  the  interpumular  plates  they  form 
the  interbrachial  area  of  the  calyx,  and  with  the  intersecundibrachs  or  interdistichals  the  inter- 


38  MESOZOIG  AND  CENOZOIC   ECHINODEKMATA   OF   THE   UNITED   STATES. 

distichal  area  of  the  calyx.  Each  mterbrachial  area  contains  in  aduUs,  usually  six  rarely  eight, 
of  these  fixed  pmnules.  In  the  young  foui'  and  even  two  have  been  found.  The  interdistichal 
area  contains  four  fixed  pinnules  in  adult  forms  and  two,  and  at  times  apparently  none,  in  the 
young.     The  amount  of  fixation  therefore  increases  with  age. 

The  interbrachial  area  consists  of  from  three  or  four  to  twenty-tlu-ee  plates.  The  arrange- 
ment of  the  plates  is  very  variable.  When  there  are  seven  plates  or  less  no  one  of  the  inter- 
brachials  is  inclosed,  but  the  plates  are  disposed  in  more  or  less  irregular  vertical  rows.  Tliis 
arrangement  holds  in  some  specimens  containing  eight  or  even  nine  or  ten  plates.  In  other 
specimens  one  or  more  plates  are  mclosed.  Variation  in  the  interbrachial  areas  occurs  in  some 
individuals. 

The  intersecundibrachs  or  interdistichals  may  differ  in  the  same  way,  the  number  var^-ing 
from  none  to  8,  although  the  most  common  number  is  from  2  to  5,  the  younger  forms  havmg  less 
than  the  adults.  The  interpinnular  plates-  are  not  present  in  all  specimens,  but  one  or  two  may 
be  placed  between  the  proximal  portions  of  the  fixed  pinnules  and  the  mtervenmg  secundibrachs. 
The  interpinnulars  generally  appear  in  corresponding  position  on  opposite  sides  of  the  same  area. 

The  arms  are  the  continuation  of  the  secundibrachs  or  distichals  and  are  therefore  ten  in 
number.  They  consist  of  brachials  and  pinnules,  the  latter  disposed  in  the  manner  previously 
described.  An  arm  branch  100  centimeters,  or  40  inches,  long  has  been  described  by  Sprmger, 
who  thinks  it  not  improbable  that  a  total  spread  of  arms  of  250  centimeters,  or  8  feet  4  inches, 
may  have  occvu-red. 

The  ventral  disk  or  tegmen  has  been  described  only  by  Springer,  who  prepared  a  number  of 
specimens  on  which  the  disk  was  beautifully  preserved.  He  states  that  it  is  composed  of  the 
jjlated  skin,  the  membrane  being  of  such  a  highlj'  carbonaceous  composition  that  it  is  jet  black 
m  the  fossil.  This  membrane  evidentty  mclosed  the  entire  visceral  mass  and  formed  a  lining 
where  it  is  usually  seen  when  the  calyx  is  broken  away.  Upon  the  disk  it  is  studded  or  paved 
with  small  calcareous  plates  or  spicules  which  are  not  connected  by  sutucre  but  are  embedded  in 
the  tegment  touching  each  other.  They  are  of  irregular  shape,  variable  in  size,  and  without  any 
definite  plan  of  arrangement. 

The  central  part  of  the  disk  is  occupied  by  a  large,  conical  anal  tube,  shaped  like  an  mverted 
fmmel,  which  i^  perhaps  an  extension  of  the  ventral  disk  above  described.  It  is  also  composed 
of  a  plated  skin,  the  granules  of  the  disks  passmg  gradually  mto  it  and  becoming  more  and  more 
elongate,  until  toward  the  distal  end  where  the  openmg  was  they  become  threadhke. 

The  mouth  is  excentric,  and  the  ambulacra  diverge  at  a  point  near  the  margin  of  the  disk. 
Two  of  them  follow  around  the  margin  in  a  large  hood-shaped  cone,  closing  the  anal  tube. 
These  branch  on  either  side  so  as  to  connect  with  the  arms  of  the  posterior  rays.  The  next  pair 
of  ambulacra  are  shorter;  they  branch  and  supply  two  lateral  rays.  A  single  groove  runs  to 
one  branch  of  the  anterior  ray  and  the  other  branch  does  not  seem  to  have  any  groove  leadmg  to 
it.  The  ambulacral  grooves  are  simply  depressions  m  the  peristome.  There  is  no  trace  of  any 
covermg  plates  or  anything  like  an  ambulacral  skeleton. 

Localities. — The  first  specimen  of  this  species  was  found  by  O.  C.  Marsh  in  the  Uinta  Moun- 
tains, Utah.  GrinneU  established  the  genus  Uintacrinus  on  much  better  preserved  material 
from  Trigo  County,  Kans.  Still  better  specimens  were  later  found  in  Logan  County,  Kans. ,  which 
has  been  the  source  of  most  of  the  fine  material  in  the  various  museums  of  the  world.  It  is  from 
this  locality  that  Springer  secured  a  few  years  ago  the  superb  specimens  that  are  the  basis  of 
his  elaborate  monograph. 

Geologic  horizon. — Niobrara  chalk.  Upper  Cretaceous. 

Collections. — Museum  of  Comparative  Zoology,  Cambridge;  U.  S.  National  Museum  (8044); 
University  of  Kansas;  Yale  University;  British  Museum;  Johns  Hopkins  University. 


CEETACEOUS   ECHINODEKMATA.  39 

Family  MARSUPITID^. 

Genus  MABSUPITES  Miller. 
Marsupites  americanus  Springer. 
Plate  VII,  figures  2a,  2b,  3. 
Marsupites  americanns  Springer,  1911,  Mus.  Comp.  Zool.  Mem.,  vol.  25,  No.  3,  pp.  158-161,  PI.  VI,  figs.  4a,  4b,  5. 
Springer  describes  the  species  as  follows : 

Determinative  characters. — Calyx  globose,  wider  than  high;  widest  about  middle  of  basal,  contracting  toward  the 
arm  bases.  Centrale  larger  than  infrabasals.  *  *  *  Radial  facets  shallow,  facing  almost  vertically;  filling  about 
half  the  distal  face  of  radial,  and  having  a  straight  muscular  articulation.  Primibrachs  2 ;  succeeding  brachials  to  the 
number  of  seven  in  the  longest  arm  preserved  wide  and  very  short,  with  an  alternating  cuneiform  arrangement  and  an 
indication  of  syzygies  betVeen  Br3  and  4;  ventral  groove  broad  and  shallow.  A  good-sized  triangular  interbrachial 
plate,  having  straight  sides  and  apparently  joined  to  the  brachials  by  suture,  fills  the  space  between  the  arm  bases.  All 
plates  very  thin,  and  covered  with  moderately  fine  radiating  strise  crossing  the  sutures  and  converging  at  the  centers; 
a  strong  ridge  runs  upward  from  the  center  of  the  basals,  two  meeting  at  each  radial  facet.     Further  structures  unknown. 

Dimensions. — Centrale:  Diameter  of  pentagon  18  millimeters;  IBB  17  millimeters  high  by  17.5  wide;  BB  18  milli- 
meters high  by  18  wide;  RR  11  millimeters  liigh  by  14  wide;  radial  facets  6  millimeters  wide.  In  a  large  fragment  the 
centrale  is  25  millimeters  wide. 

Description. — The  general  outline  and  surface  ornament  of  this  species  are  not  different  from  what  may  be  seen 
among  specimens  of  M.  testudinarius  of  the  English  chalk  from  Sussex  and  other  places.  These  vary  from  coarse  to  fine 
striae  and  with  such  a  thin,  pliant  calyx  the  contour  of  the  fossil  is  largely  a  matter  of  pressure  in  its  deposition.  Meas- 
urements of  plates  shows  no  substantial  difference  between  the  two,  an  average  of  five  specimens  of  the  English  species 
being  as  follows:  Centrale,  19.1  millimeters  wide;  IBB,  19.6  millimeters  high  by  19.5  wide;  BB,  19.6  millimeters  high 
by  20.1  wide;  RR,  12.6  millimeters  high  by  15.7  wide;  R,  facets  8  millimeters  wide.  The  only  real  difference  observ- 
able in  the  parts  preserved  is  that  in  our  species  the  brachials  are  shorter  and  wider  than  in  M.  testudinarius;  and  if  we 
had  enough  specimens  with  brachials  attached  to  get  an  average,  this  might  disappear.  The  calyx  figured  is  smaller 
than  the  English  species  usually  appears,  but  the  other  fragmentary  specimen  has  plates  fully  as  large  as  that.  The 
species  is  rare  and  has  only  been  found  at  the  type  locality. 

Locality. — ^Plymouth  Bluff,  Miss. 

Geologic  Tiorizon. — Tombigbee  sand  member  of  the  Eutaw  formation,  Upper  Cretaceous. 

Collection. — Collection  of  Frederick  Braun. 

Order  FLEXTBILIA. 

Suborder  PINNATA. 

FamUy  BOUEGUETICRINID^. 

Genus  BHIZOCBINTJS  M.  Sars. 

Rhizocrinus  alabamensis  (De  Loriol). 
Plate  VII,  figures  4ar-c. 

Bourgueticrinus  alabamensis  De  Loriol,  1882,  Cincinnati  Soc.  Nat.  Hist.  Jour.,  vol.  5,  p.  118,  PL  V,  figs.  1,  la,  lb. 
Rhizocrinus  alabamensis  Carpenter,  1884,  Challenger  Repts.,  vol.  11,  pt.  2,  p.  257. 
Bourgueticrinus  alabamensis  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Bourgueticrinus  alabamensis  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  25,  PL  III,  figs.  la-c. 

Description. — ^As  it  has  been  impossible  for  the  writer  to  obtain  possession  of  the  type  of  this 
species  the  description  of  De  Loriol,  as  translated  by  S.  A.  Miller,  is  given  verbatim: 

This  species  is  as  yet  known  only  by  the  basal  cone  wliich  supports  the  calyx,  and  which  is  composed  of  several 
enlarging  segments  of  the  column  surmounted  by  the  basal  plates.  The  height  of  the  inverted  cone  is  5  millimeters; 
the  diameter  of  the  basal  plate  is  3 J  millimeters;  and  that  of  the  inferior  segment  of  the  column  is  3  millimeters  in  its 
major  axis.  Its  form  is  faintly  swollen  in  the  middle ;  the  surface  is  smooth.  The  sutures  are  very  indistinct,  and  it  is 
a  difiicult  matter  to  determine  what  was  the  height  of  the  basal  plate.  The  superior  face  of  the  cone  carries  five  slender 
and  compatively  elevated  radiating  ridges,  which  bound  five  deep  depressions  in  which  the  basal  pieces  of  the  calyx 
were  lodged ;  in  the  center  an  enlargement  of  the  central  canal  constitutes  the  bottom  of  the  calyx  cavity.  The  articu- 
lar face  of  the  lower  joint  of  the  column  forming  the  inferior  end  of  the  cone  is  elliptical,  but  the  length  of  its  major 
axis  does  not,  however,  much  exceed  that  of  its  minor  axis.     It  is  slightly  concave  and  encircled  by  a  feeble  rim  along 


40  MESOZOIC   AND   CENOZOIC    ECHINODEEMATA   OF    THE    UNITED   STATES. 

the  circumference  line;  the  transverse  articular  ridge  process  is  reduced  to  two  elongated  tubercles  which  proceed  from 
the  marginal  rim.     Central  canal  comparatively  large. 

Although  this  species  is  still  very  imperfectly  known  one  can  affirm  that  it  is  certainly  distinct  from  Bourgiu-ticrinns 
ellipticus  Miller,  by  the  much  less  swollen  form  of  the  basal  cone,  which  is  but  slightly  convex  in  outline,  and  by  the 
facts  that  the  lower  segment  of  the  cone  is  already  elliptical  and  already  possesses  the  rudiments  of  a  transverse  articular 
ridge.  Furthermore,  the  radiating  carinse  are  very  much  more  salient,  and  consequently  the  depressions  which  they 
Beparate  very  much  deeper.     Finally,  by  its  central  canal  being  relatively  much  larger . 

This  species  is  referred  to  the  genus  Rhizocrinus,  following  the  views  of  Carpenter  and  also 
from  the  possible  close  relationship  of  the  form  to  RJiizocrinus  cylindricus  Weller  from  New  Jersey. 
Locality. — ^Livingstone,  Ala.  (De  Loriol). 
Geologic  Jiorizon. — Ripley  formation,  Upper  Cretaceous. 
Collection. — Cincinnati  Society  of  Natural  History. 

Rhizocrinus  cylindricus  Weller. 

Plate  VII,  figures  5a-g. 

Rhizocrinus  q/lindricus  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  275,  276, 
PI.  VI,  fig.  1. 

Determinative  cliaracters. — Weller  says: 

Calyx  cylindrical,  slender  and  greatly  elongate,  the  sides  almost  straight,  not  enlarging  from  the  basals  up.  The 
proximal  column  joint  (or  joints  ?)  higher  than  the  basals  and  radials  together,  cylindrical  above  with  straight  sides, 
slightly  contracted  below.  Basals  much  higher  than  the  radials.  Radial  facets  shallow,  curved,  rather  wide,  separate, 
low  and  not  sloping  upward,  having  no  conspicuous  muscle  plate  or  ligament  fossa.  They  inclose  a  relatively  large  and 
well-excavated  central  funnel  or  visceral  cavity. 

Dimensions. — Height  of  proximal  column  joint  and  calyx  together  9.3  millimeters ;  diameter 
3  millimeters;  height  of  proximal  column  joint  6  millimeters.  Isolated  joints:  width  2  to  4 
millimeters;  height  3  to  3.5  millimeters. 

Description. — This  species  is  established  on  a  single  complete  calyx  and  proximal  stem 
joint,  although  numerous  isolated  column  joints  may  belong  to  the  same  species.  Several  of 
these  column  joints  were  collected  a  number  of  years  ago  by  the  author.  Figures  of  some  of  the 
more  characteristic  ones  were  first  given  by  Weller  from  drawings  furnished  by  the  author  and 
are  repeated  here. 

Related  forms. — The  specimen  is  clearly  a  member  of  the  family  Bourgueticrinidse  and 
superficially  resembles  in  some  respects  Bourgueticrinus  ellipticus  and  B.  sequalis  from  the  White 
Clialk  of  England,  but  it  differs  from  these  species  in  the  much  greater  height  of  its  basals.  The 
character  of  the  radial  facets  and  the  larger  viceral  cavity,  however,  seem  to  remove  it  from 
that  genus.  In  the  great  height  of  its  basals  the  species  agrees  with  members  of  the  genus 
Rhizocrinus,  but  that  genus  is  described  as  having  a  thin,  disklike  proximal  stem  joint,  whereas 
the  New  Jersey  species  apparently  has  an  exceedingly  high  one  in  which  no  transverse  divisions 
can  be  detected.  There  seems  to  be  no  reason,  however,  why  some  latitude  may  not  be  allowed 
in  this  character.  The  genus  Rhizocrinus  has  not  heretofore  been  recognized  earlier  than  the 
Eocene,  but  there  is  no  reason  why  it  should  not  also  occiu-  in  the  later  Cretaceous. 

The  species  is  possibly  allied  to  Bhizocrinus  alabamensis  (De  Loriol)  but  diffe"-s  from  that 
species  m  having  a  much  more  slender  form. 

Locality. — Vinccntown,  N.  J. 

Geologic  horizon. — Vinccntown  sand  of  the  Rancocas  group.  Upper  Cretaceous. 

Collection. — New  Jersey  Geological  Survey;  Johns  Hopkins  University. 


CEETACEOUS  ECHINODEKMATA.  41 

Class  STELI.EROIDEA. 

Subclass  ASTEROIDEA. 

Order  PHANEROZOMA. 

Family  ASTROPECTINID.E. 

Genus  ASTBOPECTEN  Schiilze. 
ASTROPECTEN  (  * )  MONTANUS    DoUglas. 
Plate  VII,  figure  6. 
Astropecten  montanus  Douglas,  1903,  Carnegie  Mus.  Ann.,  vol.  2,  pp.  .5-8,  text  fig. 

Determinative  characters. — Douglas  says:  "Size  small;  arms  narrow  and  gi'adually  tapermg, 
longer  than  the  diameter  of  the  body;  five  radial  elliptical  figm-es  on  body,  all  except  one  nearly 
in  line  with  the  long  axis  of  the  arms. " 

Dimensions. — From  the  central  pit  to  end  of  perfect  arm  12  millimeters.  From  central 
pit  to  margin  of  body  between  the  arms  3.5  millimeters. 

Description. — Douglas  in  his  description  of  the  form  says  that  the  most  promment  markings 
are  the  pits  which  probably  represent  the  margmal  plates.  It  is  possible,  however,  that  these 
may  be  impressions  of  the  ambulacra.  Halfway  from  the  base  to  the  end  of  the  arm  each  row 
of  pits  is  nearly  as  wide  as  the  middle  portion  of  the  arm.  Only  one  arm  is  complete.  This  has 
12  pits  on  each  side  and  they  arc  opposite. 

Locality. — South  fork  of  Sixteenmde  Creek,  23  mUes  north  of  Bozeman,  Mont. 

Geologic  horizon. — Colorado  shale,  Upper  Cretaceous. 

Collection. — Carnegie  Museum,  Pittsburgh  (601). 

Family  PENTAGONASTERID^. 

Genus  PENTAGONASTER  Schulze. 

Pentagonaster  browni  Weller. 

Plate  VII,  figure  7. 
Pentagonaster  browni  Weller,  1905,  Jour.  Geology,  vol.  13,  pp.  257,  258,  fig.  1. 

Determinative  characters. — ^Weller  says:  " Stellato-pentagonal  in  outline.  Disk  large, 
apparently  flat.  Interradial  area  broadly  romided  and  rays  elongate  for  the  genus,  rounded  at 
the  extremities.  Marginal  plates  large,  about  sixteen  occupying  each  interradial  arc  from  tip 
to  tip  of  adjacent  rays,  the  character  of  their  ornamentation  not  preserved." 

Dimensions. — Major  radius  24  millimeters;  minor  radius  11.  4  millimeters. 

Description. — The  specimen  is  apparently  exposed  from  its  dorsal  side,  but  ajiart  from  the 
large  marginal  plates  all  the  plates  of  this  surface  have  been  destroyed.  The  impressions  of  the 
ambulacral  furrows  of  the  ventral  surface  are  exposed  by  the  weathermg  away  of  the  doi-sal  sur- 
face, and  appear  as  rounded  slightly  elevated  ridges  extending  from  the  arm  pits  to  the  center  of 
the  disk,  but  the  characters  of  the  ambulacra  are  not  sufficiently  well  preserved  to  be  accxu'ately 
determined. 

The  presence  of  highly  developed  marginal  plates  on  the  specimen  mark  it  at  once  as  a 
member  of  the  order  Phanerozonia,  and  it  may  be  placed,  without  serious  question,  in  the  family 
Pentagouasteridie.  The  reference  of  the  specimen  to  its  proper  genus  is  less  satisfactory,  but 
it  seenas  to  agree  more  closely  with  Pentagonaster  than  with  any  other,  although  the  interradial 
arcs  are  somewhat  deeper  than  is  usual  in  that  genus.  In  the  recent  species  P.  arculatus  Sladen,' 
however,  these  arcs  are  nearly  as  deep  as  in  the  fossil  specimen,  the  proportion  between  the 
minor  and  major  radii  being  1  to  1.93,  against  1  to  2.08  in  the  fossil  specimen. 

1  Challenger  Reports,  Zoology,  vol.  .30,  p.  277.  PI.  Lll.  figs.  1,2. 


42  MESOZOIC    AND   CENOZOIC    ECHIWODEKMATA    OF    THE   UNITED    STATES. 

The  sjjecimen  also  more  or  less  closely  resembles,  in  the  charactei-s  preserved,  some  of  the 
recent  species  of  Gnathaster,  a  genus  also  belonging  to  the  family  Pentagonasteridse,  in  which 
the  interradial  arcs  are  in  many  specimens  much  deeper  than  in  Pentagonaster,  the  proportion 
of  the  minor  to  the  major  radii  in  G.  elongatus  Sladen  '  being  1  to  3.5.  Gnathaster,  however,  is 
customarily  characterized  by  the  presence  of  an  odd  interradial  marginal  plate,  a  character  not 
clearly  shown  in  the  fossil  specimen.  In  one  of  the  interradia  such  a  plate  seems  to  be  present, 
but  in  the  others  not.  For  the  present,  therefore,  the  specimen  may  be  referred  to  the  genus 
Pentagonaster   (Weller) . 

Locality.— ^Y..  \  sec.  16,  T.  .32  N.,  R.  99  W.,  near  Lander,  Wyo. 

Geologic  horizon. — Montana  group.  Upper  Cretaceous. 

Collection. — Walker  Museum,  Chicago. 

FamUy  ATHENEIDJE. 

Genus  GONIASTEB  Agassiz  (em.  Per.). 
GONIASTEE   MAMMILLATA   Gabb. 

Plate  Vlll,  figures  la-h. 

Goniaster  mammillata  Gabb,  1876,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  28,  pp.  178,  179,  figs.  2,  2a,  2b. 
Goniaster  mammillata  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Goniaster  mammillata  Clark,  1893,  U.  S.  Geol.  Siu-vey  Bull.  97,  p.  32,  PI.  V,  figs.  la-h. 
Goniaster  mammillata  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  6. 

Goniaster  mammillata  Weller.  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  277-278, 
Pl.Vl,  figs.  10-17. 

Determinative  characters. — Body  pentagonal,  provided  with  a  dorsal  and  a  central  row  of 
marginal  plates  that  are  narrower  than  high,  and  distinctly  tumid  on  their  outer  surfaces.  Only 
detached  marginal  plates  preserved. 

Dimensions. — Plates:  Height  3  to  8  millimeters;  thickness  2.5  millimeters. 

Description. — Gabb  mentions  the  discovery  of  about  thirty  detached  marginal  plates  of 
this  species.  Many  more  have  been  found  by  the  author.  They  differ  widely  in  shape  from 
their  position  on  the  margin,  but  among  those  examined  the  majority  are  higher  than  wide  and 
are  swollen  on  the  outer  surfaces.  Certain  of  the  plates  show  marked  protuberances  upon  the 
general  level  of  the  plate.  The  surface  of  the  plates  is  punctate,  the  small  depressions  being 
arranged  in  rows  that  cross  one  another  at  right  angles. 

Related  forms. — No  American  forms  are  similar  enough  to  this  species  to  be  confounded  with 
it.  Lack  of  knowledge  of  all  characters  except  those  of  a  few  marginal  plates  renders  wide 
comparisons  impossible. 

Locality. — Vincentown,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collections. — Academy  of  Natural  Sciences  of  Philadelphia  (1457);  Johns  Hopkins 
University. 

Family  PENTACEROTID.E. 

Genus  PENTACEBOS  Linck. 

Pentaceros  asperulus  Clark. 

Plate  VIII,  figures  2a-b. 

Pentaceros  asperulus  Claxk,  1907 ;  in  Weller,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Siu-vey  New  Jersey,  pp.  278- 
279,  PL  VI,  figs.  18,  19. 

Determinative  characters. — ^Body  pentagonal  with  long,  narrow  arms;  covered  with  irregu- 
larly shaped  plates  that  touch  intermittently  at  their  margins,  the  surface  uneven  and  bearing 
spines.     Detached  body  plates  alone  found. 

1  Idem,  p.  288,  PI.  XLVIII,  figs.  1,  2. 


CRETACEOUS  ECHIKODEKMATA.  43 

Dimensions. — Type  specimen:  Length  6.5  millimeters;  width  4  to  5  milUmeters;  thick- 
ness 3.5  millimetei-s. 

Description. — Two  or  three  well-preserved  specimens  of  the  small  surface  plates  of  a  Penta- 
ceros  have  been  found  by  the  writer.  They  are  so  highly  characteristic  that  their  generic  rela- 
tions are  clearly  apparent.  As  no  other  Cretaceous  representatives  of  this  genus  have  been 
found  in  Aruerican  deposits  they  have  been  given  a  specific  name. 

The  plates  are  irregular  in  outline,  the  intermittent  articulating  surfaces  on  the  perimeter 
producing  a  roughly  polygonal  outline.  The  surface  of  the  plates  is  uneven,  the  irregularly 
flattened  areas  providing  attachment  for  spines.  The  central  portion  of  the  plates  is  higher  than 
the  truncated  margins. 

Related  fornix. — No  other  American  Cretaceous  representatives  of  this  genus  are  known, 
and  the  plates  can  not  readily  be  associated  with  any  known  European  species. 

Locality. — Vincentown,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collection. — Johns  Hopkins  University  (T  .3014). 

Subclass  OPHIUEOIDEA. 

Order  ZYGOPHIUR^. 

Family  OPHIOLEPIDID.E. 

Genus  OPmOGrLYPHA  Lyman. 

Ophioglypha  texana  Clark. 

Plate  VIII,  figures  3a-c. 

Ophioglypha  texana  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  30,  PI.  IV,  figs.  la-c. 

Determinative  characters. — Disk  round;  composition  indistinct.  Arms  long,  with  wedge- 
shaped  under-arm  plates  about  as  wide  as  long;  upper  arm  plates  about  twice  as  wide  as  long. 

Dimensions. — Diameter  of  disk  4  millimeters ;  length  of  arm  50  millimeters ;  width  of  arm 
at  disk  2  millimeters. 

Description. — The  determination  of  this  species  is  dependent  on  three  fairly  well  preserved 
forms  that  are  grouped  upon  a  single  slab  of  limestone,  all  with  the  lower  side  exposed.  The 
surface  upon  which  they  rest  is  considerably  weathered,  and  many  of  the  details  of  structure 
have  consequently  suffered.  The  general  form  of  the  disk  is  preserved,  although  its  composition 
can  not  be  made  out.  Many  of  the  arm  plates  have  disappeared,  leaving  only  the  skeletal 
pieces.  Where  preserved,  the  under-arm  plates  are  wedge-shaped  and  about  as  wide  as  long. 
The  upper-arm  plates,  which  are  shown  only  as  impressions  upon  the  limestone,  are  nearly  twice 
as  wide  as  long  and  have  their  lateral  edges  rounded. 

Locality. — Six  miles  north  of  Fort  Worth,  Tex.,  on  the  banks  of  Fossil  Creek.  Associated 
with  Ostrea  quadriplicata  Shumard,  Stearnsia  rohbinsi  White,  and  Leiocidaris  hemigranosus 
(Shumard). 

Geologic  horizon. — Denison  formation  of  the  Washita  group,  Comanche  series.  Cretaceous. 

Collection. — U.  S.  National  Museum  (21884). 

Ophioglypha  bridgerensis  (Meek). 

Plate  VIII,  figures  4a-b. 

Ophiodcrma'!  bridgerensis  Meek,  1873,  U.  S.  Geol.  and  Geog.  Survey  Terr.  Kept,  for  1872,  pt.  2,  p.  475. 

Ophiodenna'!  bridgerensis  White,  1883,  U.  S.  Geol.  and  Geog.  Survey  Terr.  Kept,  for  1878,  pt.  1,  pp.  8,  9,  PL  XII,  fig.  i2a. 

Ophioglypha  bridgerensis  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 

Ophiogly pha  bridgerensis  CUvk,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  29,  PI.  IV,  figs.  2a-b. 

Determinative  characters. — Disk  composed  of  numerous  small  imbricating  plates.  Upper- 
arm  plates  wider  than  long,  the  outer  angles  sharp  and  extending  between  the  side-arm  plates, 
which  are  slightly  smaller.     Under-arm  plates  long  and  nearly  rectangular  in  sliape. 


44  MESOZOIC    AND    CENOZOIC   ECHINODERMATA    OF    THE    UNITED    STATES. 

Dimensions. — Diameter  of  disk  5  millimeters;  length  of  arm  20  millimeters;  width  of  arm 
near  disk  IJ  miUimeters. 

Description. — The  single  specimen  of  tliis  species  thus  far  found  is  described  in  a  footnote  to 
a  list  of  specimens  reported  by  F.  B.  Meek  in  1872,  and  redescribed  and  figured  by  C.  A.  Wliite  in 
1878.  This  specimen,  which  has  been  carefully  examined  by  the  writer,  presents  the  upper  sui^ 
face  of  the  disk  and  fragments  of  the  five  arms.  Upon  four  of  the  fragments  the  upper  and  side 
arm  plates  are  shown,  and  upon  the  fifth  a  small  portion  of  the  under  surface  with  the  under  arm 
plates  and  ambulacral  openings  is  preserved. 

The  disk  is  described  by  Meek  as  "depressed,  nearly  circular,  showing  on  the  dorsal  side  ten 
ovate-subtrigonal  radial  plates,  that  are  joined  together  over  the  inner  ends  of  the  arms,  so  as  to 
form  five  pairs."  A  close  examination  of  the  specimen  shows  that  the  disk  is  made  up  of  numer- 
ous small  imbricating  plates,  and  that  the  supposed  division  into  ten  mentioned  by  Meek  may 
be  explamed  by  the  fractured  condition  of  the  poorly  preserved  specimen. 

The  arms  are  small  and  are,  as  stated  by  Meek,  perhaps  tliree-fourths  of  an  inch  in  length, 
although  none  of  them  are  preserved  entire.  The  upper-arm  plates  are  wider  than  long  and 
hexagonal  in  form.  The  outer  angles  are  sharp  and  are  embraced  between  the  upper  portions 
of  the  side  plates.  The  latter  are  slightly  swollen  but  are  not  shown  in  their  entire  length.  The 
lower  arms  are  poorly  preserved  but  so  far  as  exliibited  are  long  and  narrow,  nearly  rectangular 
in  shape,  and  slightly  swollen  in  their  central  portions. 

Related  forms. — Some  doubt  exists  as  to  the  generic  position  of  tliis  species.  So  many  of  the 
distinctive  characters  are  wanting  that  a  definite  determination  is  quite  impossible,  but  from  the 
apparent  structure  of  the  disk,  formed  of  numerous  imbricating  plates,  its  reference  to  Opliiogly- 
plia  seems  probable.  The  only  other  form,  0.  texana,  has,  so  far  as  can  be  discerned,  a  somewhat 
smaller  and  differently  constructed  disk,  and  both  the  upper  and  under  arm  plates  are  of  different 
shape. 

Locality.— The  "last  foot  of  Bridger  Peak,  4  miles  north  of  Fort  Ellis,  Mont."  (Meek). 

Geologic  horizon. — ^Associated  with  species  of  the  genera  Gryphsea,  Avicula,  Inoceramus, 
CrassateUa,  Pholadomya,  Turritella,  and  Gyrodes,  that  denote  the  Cretaceous  age  of  the  strata 
(Meek).     Upper  Cretaceous,  most  probably  Colorado  shale. 

Collection. — ^U.  S.  National  Museum  (7820). 

Class  ECHINOIDEA. 

Subclass  KEGULARIA  EXDOBRANCHIATA. 

Order   CIDAROIDEA. 

Faniily  CIDARID^. 

Genus  CIDABIS  Leske. 

CiDARis  TEHAMAENSis  Clark,  n.  sp. 

Plate   IX,   figure   1. 

Determinative  characters. — Test  unknown.  Spines  large  and  club-shabed,  ^\•ith  rows  of 
granules  extending  from  neck  to  point  of  spine. 

Dimensions. — Spine:  Length  30  miUimeters ;  width  in  thickest  part  12  mdhmetcrs. 

Description. — Tliis  species  is  represented  by  a  well-preserved  spine  that  is  large  and  club- 
shaped.  The  granules  are  large  and  disposed  in  rows  extending  from  the  neck  to  the  point  of 
the  spine. 

Locality. — Shelton's  ranch,  Tehama  County,  Cal. 

Geologic  Tiorizon. — Knoxville  formation,  Lower  Cretaceous. 

Collection. — U.  S.  National  Museum  (31195). 


CRETACEOUS   ECHINODERMATA.  45 

CiDARis  TEXANUS  Clark. 
Plate  IX,  figures  2a-f. 

Cidaris  ttxanus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  -i-ol.  10,  No.  87,  p.  7.5. 

Cidaris  texanus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  61. 

Cidaris  texanus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  36,  37,  PI.  VII,  figs.  la-e. 

Determinative  characters. — Test  large,  inflated.  Ambulacra  narrow,  sinuous,  with  four  rows 
of  granules  between  tlie  poriferous  avenues,  which  at  the  ambitus  are  increased  to  six  and  toward 
the  apical  system  and  peristome  are  reduced  to  two  rows.  Pores  oval,  separated  by  transverse 
elevations,  which  partially  envelop  the  openings.  Interambulacra  wide,  with  large  circular 
tubercles.  Areola  circular,  depressed;  boss  smooth;  mamelon  small,  perforated.  Miliary  space 
wide,  covered  with  numerous  small  granules. 

Dimensions. — Diameter  80  miUimeters  ( ?) ;  height  40  miUimeters  ( ?). 

Descnption. — A  large  portion  of  the  test  of  tliis  beautiful  species  is  excellently  preserved. 
All  of  the  characteristic  features,  except  those  relatmg  to  the  apical  system  and  peristome, 
are  clearl}^  shown.  The  test,  however,  is  somewhat  compressed,  so  that  the  original  form  can 
not  be  made  out  with  certainty.  The  ambulacral  areas  are  narrow  and  slightly  flexuous. 
Between  the  poriferous  avenues,  wliicli  are  iiarrow  and  depressed,  are  four  rows  of  granules  of 
nearly  equal  size,  wliich  directly  at  the  ambitus  are  increased  to  six,  and  toward  both  apical 
system  and  peristome  are  reduced  to  two.  Irregularly  scattered  among  the  rows  of  granules 
are  others  smaller  in  size.  The  pores  are  oval  and  separated  by  transverse  elevations  that 
partly  encircle  the  openings,  lea-\dng  a  depression  between  each  pair.     • 

Tlic  interambulacral  plates  are  mde  and  bear  large  circular  tubercles.  The  areola  of  each 
tubercle  is  radially  ridged,  deeply  depressed,  and  surrounded  by  a  row  of  mammUlated  granides. 
The  boss  is  sliglitly  elevated  above  the  level  of  the  plate  and  presents  a  smooth  and  sharp  ridge 
around  the  small_perforated  mamelon.  The  miliary  space  is  wide  and  tliickly  set,  with  small 
elevated  granules  of  equal  size.     The  apical  system  and  peristome  are  lacking. 

Related  forms. — At  first  sight  the  species  shows  strong  points  of  smiilarity  to  C.  sceptrifera 
Mantell  from  the  Wliite  Chalk  of  England,  although  the  arrangement  of  granules  in  its  ambula- 
cra is  different.  The  areola  of  C.  sceptrifera  is  described  as  smooth,  and  that  of  0.  texanus  as 
clearly  ridged  radially.  The  only  related  form  rejDorted  from  Texas  is  Leiocidaris  hemigranosus, 
formerly  referred  to  Cidaris,  but  which,  as  wiU  be  shown,  does  not  belong  to  that  genus.  Cida- 
ris hranneri,  from  Brazil,  described  by  Wliite,  is  allied  to  0.  texanus,  but  differs  from  it  in  the 
character  of  the  areola  and  the  arrangement  of  granules  in  both  the  ambulacral  and  interam- 
bulacral areas. 

Locality. — Bexar  County,  Tex. 

Geologic  horizon. — Washita  group  of  the  Comanche  series.  Cretaceous. 

Collection. — U.  S.  National  Museum  (8381). 

Cidaris  walcotti  Clark. 
Plate  IX,  figures  3a-d. 

Cidaris  walcotti  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 
Cidaris  walcotti  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  .51. 
Cidaris  walcotti  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  37,  38,  PI.  VI,  figs.  4a-d. 
Cidaris  walcotti  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  6. 

Cidaris  walcotti  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  281-282,  PI.  VII, 
figs.  10-13. 

Determinative  characters. — Test  small,  inflated.  Amljulacral  areas  narrow,  sinuous,  \vith 
four  rows  of  granules  between  the  depressed  poriferous  avenues.  Interambulacral  areas  l)road; 
each  tubercle  with  depressed  circular  areola,  smooth  boss  and  small  imperforate  mamelon. 
Miliary  space  wide,  thickly  covered  with  small  granules. 

Dimensions. — Type  specimen:  Height  about  25  millimeters;  width  about  37.5  millimeteis. 
39800°— 15 4 


46  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA    OF    THE   UNITED    STATES. 

Description. — The  fragments  of  this  form  examined  are  sufficiently  distinctive  to  separate 
it  from  other  species.  A  nearly  complete  interambulacrum  with  tlie  adjoining  ambulacra 
shows  that  the  test  of  the  species  is  small  and  in  a  marked  degree  inflated. 

The  ambulacra  are  naiTOW,  slightly  sinuous,  and  provided  \v'ith  four  nearly  equal  rows  of 
granules  between  the  poriferous  avenues.  On  some  additional  granules  are  irregularly  inter- 
spersed. The  poriferous  avenues  themselves  are  narrow,  deeply  depressed,  and  slightly  sinuous. 
The  pores  are  round,  with  funnel-shaped  openings,  j^roduced  by  the  intersecting  ridges.  These 
ridges,  which  separate  the  individual  pores  and  the  pore  paii-s,  give  a  lattice-like  appearance  to 
the  poriferous  zones. 

The  interambulacral  plates  are  moderately  large.  On  accbunt  of  the  indistinctly  marked 
sutures  the  small  tubercles  and  numerous  granules  cause  a  very  even  surface  over  the  entire 
interambulacrum.  The  tubercles  are  circular  and  stand  nearer  the  outer  margin  of  the  plates 
than  the  inner.  The  areolas  are  deeply  depressed,  the  central  portion  but  slightly  exceeding  the 
margin  in  height.  The  boss  is  smooth  and  stands  but  little  above  the  level  of  the  plate.  The 
mamelon  is  imperforate.  The  wide  mUiary  space  is  covered  with  a  large  number  of  irregularly 
arranged  granules  of  equal  size.  The  broken  specimens  afford  no  information  as  to  the  character 
of  the  apical  system  or  peristome. 

Related  forms. — The  species  is  very  readily  separated  from  0.  splendens,  the  only  other 
representative  of  tliis  genus  thus  far  reported  from  the  Atlantic  coast  Cretaceous,  by  its  pos- 
session of  imperforate  mamelons  and  %vide  mihary  sjDaces,  over  which  tl>e  granules  are  regularly 
scattered.     The  even  surface  of  the  test  is  likewase  a  distinguishing  feature. 

Localities. — Timber  Creek  (type)  and  Vincento\vn,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1451 ) ;  Johns  Hopkins  University. 

CiDARIS    SPLENDENS    MortOU. 

Plate  IX,  figures  4a-b,  5a-f,  6. 

Cidaris  (?)  sp.  Morton,  1829,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  Ist  ser.,  vol.  6,  p.  123. 

Echinus  sp.  Morton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.  17,  p.  287;  vol.  18,  PI.  Ill,  figs.  12, 13. 

Cidarites  splendens  '  Morton,  1841,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  1,  p.  132. 

CidaritesarmigerMorton,  1842,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  let  ser.,  vol.  8,  p.  215,  PL  II,  fig.  1. 

Cidaris  armiger  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous  formation,  p.  18. 

Cidaris  splendens  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous  formation,  p.  18. 

Cidaris  armigera  Agassiz,  1874,  KeA'ision  of  the  Echini,  p.  761. 

Cidaris  armiger  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 

Cidaris  splendens  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 

Cidaris  splendens  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  33-35,  PI.  VI,  figs.  3a-g. 

Cidaris  splendens  Johnson,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  "6. 

Cidaris  splendens  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  279-281. 

Determinative  characters. — Test  of  moderate  size,  spheroidal.  Ambulacral  areas  narrow, 
flexuous,  with  four  rows  of  granules  between  the  pore  paire,  the  outer  rows  larger  than  the  inner; 
imperfectly  defined  granules  also  appear  between  the  pores  of  each  pair.  Interambulacral  areas 
very  wide,  with  seven  or  ^ight  plates  in  each  column,  each  plate  bearing  a  tubercle  of  large  size 
characterized  by  a  wide  circular  areola,  smooth  boss,  and  small  perforated  mamelon.  Miliary 
area  small  and  covered  with  numerous  tluckly  set  granules  of  small  size.  Sutures  sharply 
defined,  depressed.  Spines  elongated,  cylindrical,  with  longitudinal  rows  of  sharp  denticulated 
processes. 

Dimensions. — Height  21.9  to  23  millimeters;  width  34.4  to  40  millimeters. 

Description. — The  first  mention  of  this  form  is  made  by  Morton  in  1829,  when  he  doubtfully 
referred  a  few  fragments  to  C!idaris  without  an  attempt  at  specific  determination.  Several  of  the 
more  important  characters  were  then  given,  but  as  the  material  examined  included  only  detached 
plates  and  a  few  spines  the  description  necessarily  lacked  much  of  completeness.  In  1841  he 
proposed  the  name  Cidarites  splendens  and  then  more  accurately  defined  the  species.     In  1842 

1  Morton  doubtless  intended  to  use  the  term  splendens  instead  of  splendeus,  which  is  probably  a  typographic  error.     In  the  publication  of 
1S42,  where  armiger  is  substituted,  the  form  spUndens  is  used. 


CEETACEOUS   ECHINODEEMATA.  47 

he  redescribed  and  now  for  the  first  time  figured  the  same  form  as  Cidarites  armiger,  a  name  which 
he  stated  lie  desired  substituted  for  C.  splendens.  Gabb  in  1859  employed  both  names,  mistaking 
them  for  independent  species,  but  refers  to  C.  splendens  as  C.  splendeus.  The  specimens  exam- 
ined by  the  writer  were  chiefly  detached  plates,  although  one  nearly  complete  test  and  two  entire 
or  nearly  entire  interambulacral  areas,  with  parts  or  all  of  the  adjoining  ambulacra,  were  also 
among  this  material.  In  these  specimens  the  oral  side  is  slightly  more  depressed  than  the  aboral, 
although  not  to  the  extent  exhibited  in  Morton's  figure.  Tire  ambulacral  areas,  which  are  nar- 
row and  flexuous,  have,  between  the  poriferous  avenues,  four  granules.  In  the  center  of  each 
column  of  plates  these  granules  are  approximately  of  equal  size,  the  outer  rows  slightly  larger, 
but  toward  the  disk  or  toward  the  peristome  tlie  inner  rows  abruptly  diminish  in  size  and  finally 
disappear.  The  pores  are  oval  in  shape  with  funnel-like  opeaiings  exteriorly.  Each  row  of 
pores  is  separated  from  that  which  accompanies  it  in  the  same  avenue  by  a  row  of  imperfectly 
defined  granules  that  form  an  undulating  ridge. 

The  interambulacral  areas  are  very  wide  and  bear  large  tubercles,  each  of  which  covers 
the  greater  portion  of  its  plate.  Upon  the  larger  plates,  in  the  center  of  each  column  the 
ai'eolas  are  circular,  but  become  somewhat  oval  toward  both  disk  and  peristome.  The  outer 
edge  of  each  areola  is  surrounded  by  a  circle  of  large  granules  that  give  it  a  crenulated  apjDearance. 
The  areola  rises  from  its  depressed  margin,  gradually  at  first,  then  rapidly,  to  the  boss,  which 
reaches  a  marked  elevation  above  the  general  level  of  the  plate.  The  boss  is  of  moderate  width 
and  smooth.  Fi'om  its  center  rises  the  mamelon,  which  is  small,  perforated,  and  slightly 
flattened  upon  the  upper  surface.  The  mihary  space  i§  covered  by  small  granules,  which  are 
most  numerously  developed  along  the  median  line  of  the  interambulacra. 

None  of  the  specimens  affords  the  apical  system.  Strong  auriculae  show  the  presence  of 
powerful  jaws. 

The  spines  are  slender,  elongated,  cylindrical,  with  longitudinal,  serrated  ribs  that  graduaUy 
become  obsolete  toward  the  base.  The  collar  is  short  and  finely  striated  longitudinally.  Tlie 
acetabulum  is  bordered  by  a  smooth  margin  and  is  perforated  in  the  center. 

Related  forms. — In  many  particulars  Oidaris  splendens  (Morton)  resembles  C.  serrata  Desor 
of  the  European  Cretaceous,  but  differs  from  it  in  several  others  notably  in  having  only  four 
rows  of  granules  between  the  poriferous  avenues. 

iocaZi^ies.— Timber  Creek  (type)  and  Vincento^vn  (figured  specimens),  N.  J. 

Geologic  horizon. — Vmcentown  sand  of  the  Rancocas  group.  Upper  Cretaceous. 

CoZZec^ions.^Philadelphia  Academy  of  Natural  Sciences;  Johns  Hopkins  University 
(T3002). 

CiDAEis  DixiENSis  Cragin. 

Plate  IX,  figures  7a-b. 

Cidaris  dixiensis  Cragin,  1893,  Geol.  Survey  Texas  Fom-th  Ann.  Kept.,  p.  146.  PI.  XLVI,  figs.  15,  16. 

Determinative  characters. — Cragin  says : 

Test  rather  small,  thin;  tubercles  perforate,  notcrenulate,  rather  small  and  feebly  elevated;  areolfp  feebly  depressed' 
interambulacral  plates  oi'namented  with  crowded  rounded  granules  which  increase  in  size  (in  the  smaller  plates,  Grad- 
ually) toward  the  areola,  the  largest  granules  forming  an  alternating  double  row  around  it. 

Dimensions. — Height  of  interambulacral  plates  6  to  7  niilhmeters;  width  7  to  8  millimeters. 

Description. — The  isolated  interambulacral  plates,  which  are  the  only  portions  of  the  test 
known,  incUcate  that  the  form  was  not  in  all  probabiUty  a  large  one.  The  tubercles  are  but 
sUghtly  elevated,  and  the  areolae  are  feebly  depressed.  The  mamelon  is  small  and  perforated. 
Tlie  boss  is  smooth.  The  miliary  space  is  relatively  narrow,  covered  with  granules  larger  toward 
the  areola,  where  they  form  an  alternating  double  row  around  it. 

Related  forms. — The  characters  given  separate  this  species  from  all  of  the  American  species  with  which  the  writer 
is  acquainted.  In  the  fades  of  the  interambulacral  portion  of  the  test,  it  bears  considerable  resemblance  to  C.  serrijer 
Forbes,  from  which  it  differs  in  the  form  of  the  plates. 

Locality. — Nine  miles  northeast  of  Dallas,  Tex. 

Geologic  horizon. — Taylor  marl,  Upper  Cretaceous. 
Collection. — Geological  Survey  of  Texas. 


48  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA   OF   THE   UNITED   STATES. 

?  CiDARIS    NAHALAKENSIS    De  Loriol. 

Cidaris  nahalahensis  De  Loriol,  1887,  Recueil  zool.  Suisse,  vol.  4,  pp.  388,  389,  PI.  XVII,  figs.  3^. 
ICidaris  nahalakensis  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  93. 

The  species  is  based  by  P.  de  Loriol  on  fragments  of  spines  obtained  from  the  Selma  chalk 
("Rotten  Hmestone")  of  the  Upper  Cretaceous  of  Wahalak,  Kemper  County,  Miss.  Similar 
spines  have  been  recognized  by  the  writer  from  other  locaUties,  but  whether  tliey  represent  an 
independent  species  or  one  hitherto  described  is  not  clear. 

Genus  LEIOCIDABIS  Desor. 

Lbiocidaeis  hemigranosus   (Shumard). 

Plate  X,  figures  la-g;  Plate  XI,  figures  la-b. 

Cidaris  hemigranosus  Shumard,  1860,  St.  Louis  Acad.  Sci.  Trans.,  vol.  1,  p.  609. 

Cidaris  hrmigranosiisUeek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 

Cidaris  hemigranosus  White,  1883,  U.  S.  Geol.  and  Geog.  Survey  Terr.  Twelfth  Ann.  Kept.,  for  1878,  p.  38,  PI.  XVIII, 

figs.  2a-b. 
Leiocidaris  heviigranosus  Clark.  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 
Leiocidaris  hemigranosus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  38,  39,  PI.  VII,  figs.  2a-d;  PI.  VIII.  figs,  la-lj; 

PI.  IX,  figs.  la-c. 
Leiocidaris  hemigranosa  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rapt.,  p.  160,  PL  XLVI,  fig.  4. 
Leiocidaris  hemigranosus  Hill,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  7,  pp.  252,  266,  272. 

Determinative  characters. — Test  v'ery  large,  subspherical.  Ambulacra  narrow,  sinuous, 
with  six  rows  of  granules  in  the  middle.  Poriferous  avenues,  wide,  deeply  depressed.  Pores 
of  each  pair  united  by  clearly  defined  furrow.  Interambulacra  broad.  Tubercles  very  large; 
areola  circular  or  slightly  polygonal,  depressed;  boss  smooth,  mamelon  large,  perforated. 
Miliary  space  covered  with  large  scattered  oval  granules.     Sutures  clearly  marked,  depressed. 

Dimensions. — Diameter  90  millimeters;  height  67  milhmeters. 

Description. — The  form,  which  was  quite  fully  described  by  Shumard  in  1860,  but  not 
fio-ured,  was  incorrectly  referred  to  the  genus  Gdaris,  from  which  it  is  separated  by  the  presence 
of  furrows  uniting  the  pores  of  each  pair.  In  tliis  respect  it  is  a  typical  representative  of  the 
genus  Leiocidaris  of  Desor.  A  very  good  illustration  was  given  by  Wliite  in  1SS3  (report  for 
1878),  although  necessarily,  from  the  size  of  the  figure,  the  furrows  connecting  the  pores  could 
not  be  very  distinctly  shown.  This  species  is  the  largest  ecliinoid  known  from  the  Texas  Cre- 
taceous, and  with  possibly  a  single  exception  the  largest  from  the  American  Mesozoic.  In  one 
unusually  fine  specimen  the  test  is  subspherical,  although  considerably  broader  and  more  flat- 
tened on  the  oral  than  aboral  side.  • 

The  ambulacra  are  narrow  and  sinuous,  with  six  rows  of  granules  between  the  poriferous 
avenues.  The  regular  arrangement  of  the  granules  is  not  persistent,  the  number  being  increased 
irreo-ularlv  near  the  middle  of  the  column  and  somewhat  reduced  toward  the  apical  system  and 
peristome.  The  poriferous  avenues  are  wide  and  deeply  depressed,  the  pores  of  each  pair  being 
united  by  a  shallow  furrow. 

The  interambulacra  are  wide  and  the  plates  of  massive  size.  The  tubercles  occupy  the 
center  of  the  plates  and  are  large  and  prominent.  The  areolas  are  deeply  depressed,  subcir- 
cular  or  sUghtly  polygonal,  and  occupy  more  than  half  of  the  greatest  diameter  of  the  plates. 
On  all  the  specimens  examined  the  areolas  show  perfectly  smooth  surfaces,  although  Shumard 
mentions  the  occurrence  of  radiating  ridges.  Toward  the  center  each  areola  rises  to  form  the 
boss,  which  is  provided  marginally  with  a  sharp  smooth  ridge.  Tlie  mamelon  is  large,  sub- 
spherical, with  a  deep  perforation  upon  its  summit.  The  mihary  space  is  wide  and  covered  with 
large,  irregularly  shaped  and  flattened  granules,  some  round  and  some  oval  in  form.  Inter- 
spersed among  these  are  much  smaller  granules,  which  increase  in  number  along  the  margin  of 
the  plates.     The  apical  system  and  peristome  are  wanting. 

Related  forms. — The  species  is  readily  separated  from  any  liitherto  described  from  American 
or  European  strata.     Its  characters  are  well  defuied  and  distinctive. 


CEETACEOUS  ECHINODERMATA.  49 

Localities. — Upper  part  of  the  bluff  of  Red  River,  Lamar  County,  and  10  iniles  above  the 
mouth  of  Kiamesha  Creek  (type) ;  3  miles  west  of  Denison  (figured  specimen) ;  railroad  cut 
west  of  Austin;  and  "Gap,"  Travis  County,  Tex. 

Geologic  horizon. — Denison  formation  of  Washita  group,  Comanche  series.  Cretaceous. 

Collection. — U.  S.  National  Museum  (21768). 

Subclass  REGUT^ARIA  ECTOBRANCTIIATA. 

Order  BIABEMOIDEA. 

Suborder  CALYCINA. 

Family  SALENIID.f;. 

Genus  SALENIA  Gray. 

Salenia  texana  Credner. 

Plate  XII,  figures  la-i ;  Plate  XIV,  figures  la-c. 

Cidaris  diatretum  Giebel,  1853,  Naturwiss.  Ver.  in  Halle  Jahresb.  for  1852,  p.  374,  PI.  VII,  figure  2. 
Salenia  texana  Credner,  1875,  Zeitschr.  fiir  gesam.  Naturwiss.,  vol.  46,  pp.  105-116,  PI.  V,  figs.  1-6. 
Salenia  texana  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 
Salenia  texana  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Salenia  texana  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  40,  41,  PL  X,  figs.  la-h. 
Salenia  texana  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  pp.  163, 164. 

Determinative  cJiaracters. — Test  subglobose;  upper  surface  convex;  sides  inflated;  under 
surface  flat.  Ambulacra  narrow,  flexuous,  with  two  rows  of  mammillated  granules  in  each  area; 
poriferous  zones  flexed;  pores  uniserial.  Interambulacra  wide,  with  two  rows  of  alternating 
plates,  six  in  each  row.  Apical  system  large,  convex,  subcircular;  periproct  prominent.  Peri- 
stome moderately  large. 

Dimensions. — Diameter  10  to  25  millimeters;  height  7  to  20  milUmeters. 

Description. — Credner  presents  tlie  first  complete  diagnosis  of  a  North  American  Mesozoic 
echinoid  in  the  detailed  descriptions  accorded  the  present  species.  Its  reference  by  Giebel  in 
1852  to  Cidaris  diatretum  (  =  Pseudodiadema  diatretum)  was  erroneous. 

The  test  is  subspherical  wlien  complete,  but  in  many  of  the  specimens  examined  is  somewhat 
flattened,  both  actinally  and  abactinally.  The  lower  surface  is  slightly  concave  in  the  vicinity 
of  the  peristome.  The  sides  are  inflated,  presenting  a  rounded  surface  which  is  fuller  above 
than  below. 

The  ambulacra  are  narrow,  increasing  gradually  in  width  from  the  apical  system  to  the 
peristome.  Two  rows  of  mammillated  granules,  twenty-four  to  twenty-six  in  each,  occupy  the 
middle  of  each  area.  Very  minute  granules  extend  in  a  hne  between  the  rows  and  in  the  vicinity 
of  the  peristome  surround  the  larger  granules  themselves.  The  poriferous  zones  are  narrow  and 
flexuous,  and  the  pores  are  regularly  arranged  in  a  uniserial  series ;  near  the  peristome  they  are 
slightly  more  crowded.  The  most  pronounced  flexure  is  opposite  the  second  interambulacral 
plate  from  the  apical  system.     Toward  the  peristome  the  zones  become  nearly  straight. 

The  interambulacra  are  broad  and  formed  of  two  alternating  rows  of  broad  plates,  six  in 
each  row.  The  tubercles  increase  rapidly  in  size  from  the  peristome,  where  tliey  are  scarcely 
larger  than  the  mammillated  granules  of  the  ambulacra.  Tlie  areolas  are  large  and  surrounded 
by  mammillated  granules  of  various  sizes  that  are  crowded  together  along  the  inner  edge  of  the 
plates.  Between  the  larger  granules  are  numerous  minute  granules.  The  areola  rises  to  a  prom- 
inent boss  that  is  deeply  crenulated  and  bears  an  imperforate  mamelon. 

The  apical  system  is  very  large,  convex,  subcircular,  with  radiating  ridges  that  extend  from 
the  ovarial  openings  of  each  plate  and  unite  with  similar  ridges  of  adjacent  plates.  Small  punc- 
tures are  found  at  the  angles  of  tlio  plates  and  intermediate  between  them.     The  subanal  plate 


50  MESOZOIC   AND    CEXOZOIC   ECHINODEKMATA   OF    THE    UNITED    STATES. 

is  situated  before  the  periproct  and  occupies  the  center  of  the  disk.     The  periproct  is  subellipti- 
cal,  rounded  anteriorly,  angular  posteriorly,  and  slightly  elevated  at  the  border. 

The  adoral  surface  is  fiat  and  the  peristome  large,  covering  nearly  one-half  the  diameter  of 
the  test.  The  peristome  is  circular,  M'ith  ten  incisions  upon  the  edge  that  divide  it  into  nearly 
equal  sized  lobes. 

Related  forms. — Credner  in  discussing  the  affinities  of  this  form  considers  it  to  be  closely 
related  to  Salenia  petalifera  Defrance  and  S.  desori  Wright.  It  is  somewhat  more  elevated  than 
S.  petalifera,  the  radial  ridges  on  its  apical  system  are  more  pronounced,  and  its  ocular  plates 
enter  more  compactly  into  the  composition  of  its  disk.  From  S.  desori,  on  the  other  hand,  it 
differs  more  mdely,  both  in  the  character  of  the  test  plates  and  the  decorations  of  the  apical 
system.     Witli  S.  scutigera  Gray  it  shows  some  points  in  common. 

Localities. — Cileola,  Comanche  spring  (figured  specimen  A) ;  Bosque  County  (figured  speci- 
men B);  2h  miles  north  of  Denison;  5  miles  west  of  Kent;  Bexar  County;  Round  Rock;  Wil- 
liamson County,  Tex. 

Geologic  horizon. — Fredericksburg  and  Washita  groups  of  the  Comanche  series.  Cretaceous. 

Collections.— v.  S.  National  Museum  (S329,  A);  Boston  Society  of  Natural  History;  Jolins 
Hopkins  University  (T3003,  B). 

Salenia  tumidula  Clark. 
Plate  XIII,  figures  la-j. 

Salenia  tumidula  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 
Salenia  tumidula  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Salenia  tumidula -Cluvk,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  41,  42,  PL  XI,  fig.^.  .la-j. 
Salenia  tumidula  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  G. 

Salenia  tumidulaVfeller,  1907,  Cretaceous  paleontolog3'of  New  Jersey;  GeoL^urvey  New  Jersey,  pp.  282,  283,  PI.  VIII, 
figs.  1-10. 

Determinative  characters. — Test  small,  subglobose;  outline  of  upper  surface  regularly  convex. 
Ambulacra  narrow,  nearly  straight,  with  two  rows  of  mammillated  granules  between  the  pore 
pairs;  poriferous  zones  sliglitl}^  flexed;  pores  uniserial.  Interambulacra  ^ide,  composed  of  two 
alternating  rows  of  five  or  six  plates.  Apical  system  large,  regularly  convex,  subcircular; 
periproct  slightly  elevated.     Peristome  small. 

Dimensions. — Diameter  2  to  13  niilhmeters;  height  1  to  10  milhnieters. 

Description. — The  perfectly  preserved  specimens  of  this  beautiful  species  jDcrmit  determi- 
nation of  all  the  details  of  structure. 

The  general  form  of  the  test  is  subglobose.  The  sides  are  inflated  and  regularly  curved, 
rising  into  a  convex  upper  surface,  from  wliich  the  periproct  projects  but  slightly.  Tlie  lower 
surface  is  abnost  flat  and  toward  the  peristome  is  slightly  depressed. 

The  ambulacra  are  rather  broad,  increasing  in  width  from  the  apical  system  to  the  peristome. 
Extending  along  the  center  of  each  area  are  two  rows  of  mammillated  granules,  15  or  16  in  each 
row,  between  which  are  other  minute  granules.  The  poriferous  zones  are  narrow  and  nearly 
straight;  the  pores  round,  regularly  arranged  in  a  uniserial  series,  and  largest  in  the  middle 
of  the  column. 

The  interambulacra  consist  of  two  rows  of  alternating  plates,  five  or  six  in  each  row.  The 
larger  tubercles  diminish  rapidly  in  size  toward  the  mouth  edges,  and  are  ver}-  indistinct  on  the 
plates  bordering  the  same.  Each  areola  is  large  and  circular,  the  boss  crenulated,  and  the  mame- 
lon  flattened  and  imperforate.  The  miliar}^  space  is  bordered  with  oval  granules  of  irregular  size 
and  arrangement,  although  most  numerous  between  the  rows  of  tubercles.  The  sutures  of  the 
plates  are  very  indistinctlj'  marked. 

The  apical  system  is  prominent,  subcircular,  with  a  regularly  curved  convex  surface,  from 
which  the  anal  aperture  projects  but  sUghtty.  The  granular  decorations  of  the  surface  often 
coalesce  and  appear  as  broken  ridges  extending  radially  from  the  five  openings  in  the  genital 
plates.  The  periproct  is  oval,  slightly  pointed  below,  and  projects  but  sUghtlj'  above  the  level 
of  the  apical  system.  It  is  bordered  bj-  a  flangefike  edge  that  is  formed  of  the  anal  and  two 
genital  plates. 


CRETACEOUS  ECHINODEEMATA.    •  51 

The  peristome  is  small,  occupying  scarcely  two-fifths  of  the  diameter  of  the  test.  Ten 
incisions  divide  the  edge  into  lobes,  the  ambulacral  lobes  projecting  the  farther. 

Related  forms. — The  identity  of  tliis  species  is  readily  established  by  the  straight  poriferous 
zones  and  pecuUar  decorations  of  the  apical  system.  The  number  of  mammillated  granules  in 
the  ambulacral  areas  is  less  than  in  S.  texana,  and  the  oval  granules  of  the  interambulacral  areas 
are  readily  distinguishable  from  the  round  forms  of  S.  bellula.  The  periproct  also  projects  far 
less  than  in  S.  texana,  although  in  this  respect  it  is  not  unUke  S.  bellula. 

Locality. — Timber  Creek,  near  Vincentown,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collections. — Academy  of  Natural  Sciences  of  Pliiladelphia  (1448) ;  Johns  Hopkins  Univei-sity. 

Salenia  bellula  Clark. 

Plate  XIII,  figures  2a-g. 

Salenia  bellula  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 
Salenia  bellula  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Salenia  bellula  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  43,  44,  PL  XI,  figs.  2a-g. 
Salenia  bellula,  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  6. 

Salenia  bellula  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  283-284,  PI.  VIII, 
figs.  11-17. 

Determinative  characters. — Test  small,  compressed,  circular;  upper  surface  convex;  sides 
inflated;  under  surface  flat.  Ambulacra  rather  broad,  nearly  straight,  with  two  rows  of  gran- 
ules in  each  row;  poriferous  zones  broad,  very  slightly  flexed;  pores  round,  uniserial.  Interam- 
bulacra  wide.     Apical  system  convex  and  nearly  circular.     Peristome  small. 

Dimensions. — Diameter  6  to  S  millimeters;  height  10  to  1.3  millimeters. 

Description. — This  Salenia  is  a  very  rare  form,  only  a  few  specunens  having  come  under  the 
notice  of  the  writer.  Certain  peculiarities  of  outline  and  structure  prevent  its  being  confounded 
with  other  species  heretofore  described. 

In  general  outhne  the  test  is  somewhat  flattened;  the  upper  surface  is  regularly  convex;  the 
sides  are  inflated;  the  lower  surface  is  flat  or  slightly  concave  at  the  peristome. 

The  ambulacra  are  prominent  and  change  but  slightly  in  width  from  the  apical  system  to 
the  peristome.  Two  rows  of  mammillated  granules,  15  in  each,  occupy  the  center  of  each 
area. 

The  interambulacra  are  wide  and  consist  of  two  rows  of  alternatmg  plates,  five  or  six  in 
each.  The  tubercles  are  prominent,  but  decrease  rapidly  in  size,  the  boss  narrow  and  indistinctly 
crenulated,  and  the  mammalon  small,  flattened,  and  imperforate.  An  indistinct  circle  of  mam- 
millated granules  surrounds  each  tubercle.  They  unite  to  form  a  sinuous  double  series  between 
the  rows  of  tubercles.  Between  the  larger  granules  are  scattered  irregularly  numerous  small 
granules  that  are  crowded  together  along  the  central  line  of  the  interambulacra. 

The  apical  system  is  shghtly  convex,  the  periproct  interfering  but  little  with  the  regularity 
of  the  curved  surface.  The  periproct  is  subcircular,  with  a  flangelike  rim.  The  plates  are 
decorated  with  oval  granules  arranged  in  radial  rows  extending  from  tlie  opening  of  each  genital 
plate  and  unite  with  corresponding  rows  of  adjacent  plates  at  the  suture. 

The  peristome  is  small,  being  one-tliird  of  the  transverse  diameter  of  the  test.  Ten  weak 
incisions  divide  the  edge  into  lobes  that  are  nearly  of  equal  size. 

Related  forms. — This  species  is  quite  distinct  fi'om  Salenia  texana  or  S.  tumidvla,  and  at  the 
same  time  does  not  admit  of  reference  to  any  of  the  European  species.  It  is  most  closelj'  related 
to  S.  tumidula,but  is  more  compressed,  has  a  differently  shaped  and  decorated  apicalsystem,  and 
has  round  and  mammillated  granules  in  the  miliary  space,  whereas  those  of  S.  tumidtda  are  char- 
acteristically oval. 

Locality. — Timber  Creek,  near  Vincentown,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collections. — Academy  of  Natural  Sciences  of  Philadelphia  (1446);  American  Museum  of 
Natural  History,  New  York. 


52  MESOZOIC   AND   CENOZOIC   ECHINODERMATA    OF    THE   UNITED    STATES. 

Suborder  ARBACINA. 
Family  HEMICIDARID.E. 

Genus  HYPODIADEJIA  Desor. 
Hypodiadema  elegans  Clark,  n.  sp. 
Plate  XIV,  figures  2a-b. 

Determinatwe  characters. — Test  small,  moderately  inflated,  slightly  tumid  above  the  ambitus. 
Ambulacra  narrow,  nearly  straight,  with  small  perforate,  crenulate  tubercles  diminishing  in  size 
from  the  ambitus  aborally.  Interambulacra  broad,  with  moderately  large  tubercles  perforate 
and  crenulate.  Apical  system  prominent,  genital  plates  large,  forming  a  periproctal  ring;  ocular 
plates  small,  elevated. 

Dimensions. — Diameter  13.5  millimeters. 

Description. — Only  a  single  specimen  of  this  species  has  been  found.  The  abactinal  and 
central  portions  of  the  test  are  well  preserved,  but  the  actinal  surface  is  covered.  The  deUcately 
sculptured  test  is  small,  somewhat  inflated  above.  The  ambulacra  are  nearly  straight  and  nar- 
row. The  small  primary  tubercles  at  the  ambitus  are  perforate  and  crenulate,  but  diminish  in  size 
toward  the  apical  system. 

The  iiiterambulacra  are  broad,  the  primary  turbercles  large,  crenulate,  and  perforate,  the 
depressed  areolas  being  surrounded  by  a  circle  of  granules.  The  miUary  space  is  narrow,  except 
toward  the  apical  system,  where  it  is  large  on  the  abutting  plates.  The  apical  system  is  elevated 
and  pronounced.  The  large  genitals  which  form  the  periproctal  ring  are  perforated,  the  madre- 
porite  having  two  large  openings.     The  oculars  are  small  and  elevated. 

Locality. — Junction  of  Muddy  and  Clear  forks  of  Little  Missouri  River,  3  miles  west  of  Mur- 
freesboro.  Pike  County,  Ark. 

Geologic  horizon. — Trinity  sand  of  the  Comanche  series,  Cretaceous. 

Collection. — \]>.  S.  National  Museum  (31196). 

Genus  GONIOPYGTJS  Agassiz. 

GoNioPYGXJS  ziTTELi  Clark. 

Plate  XIV,  figures  3a-c;  Plate  XV,  figures  la-h. 

Goniopygus  zitlelli  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 

Goniopygus  zitlelli  Clark,  1893,  Johns  Hopkins  Tniv.  Circ,  vol.  12,  No.  103,  p.  51. 

Goniopygus  2itteniC]&Tk,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  53,  54,  PI.  XVIII,  figs.  2a-d;  PI.  XIX,  figs.  la-e. 

Goniopygus  zitteli  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Kept.,  p.  155. 

Determinative  cJiaracters. — Test  subconical,  circular  in  outhne;  upper  surface  elevated;  base 
flattened.  Ambulacra  broad,  with  a  double  row  of  alternating  tubercles,  18  to  20  in  each  series; 
poriferous  zones,  with  a  double  row  of  pores,  multipUed  at  the  peristome.  Interambulacra 
broader  than  the  ambulacra,  with  a  double  row  of  pi-imary  tubercles,  10  to  12  in  each  row. 
Apical  system  prominent,  compact.     Peristome  large,  with  shallow  incisions. 

Dimensions. — Diameter  25  to  38  millimeters;  height  15  to  25  millimeters. 

Description. — All  specimens  examined  hj  the  writer  have  a  distinctly  subconical  form  that  is 
highly  characteristic.  The  upper  surface  is  very  much  elevated,  while  the  lower  is  fiat  and 
slightly  depressed  around  the  peristome. 

The  ambulacra  are  broad,  increasing  regularly  m  width  from  the  apical  disk  to  the  ambitus, 
beyond  which  they  decrease  toward  the  peristome.  There  is  a  double  row  of  18  to  20 
tulsercles  in  each  area  that  rapidly  increase  in  size  fi-om  the  apical  system  downward.  The  pores 
are  arranged  in  a  double  row  on  each  poriferous  zone,  except  in  the  ^^cinity  of  the  peristome,  where 
they  become  suddenly  increased  in  number. 

The  interambulacra  are  about  one  and  one-half  times  the  width  of  the  ambulacra,  and  each 
contains  a  double  row  of  large  tubercles,  10  to  12  in  each  series.  These  tubercles  are  con- 
siderably larger  than  those  of  the  ambulacral  area,  and  have  wide  circular  areolas,  smooth  bosses, 
and  imperforate  mamelons.     On  the  base  the  tubercles  of  all  the  areas  are  of  nearly  equal  size. 


CRETACEOUS  ECHINODERMATA.  '  53 

The  miliary  space  is  wide,  very  nearly  smooth  in  the  upjaer  portions  of  the  column,  and  sparsely 
covered  Anth  granules  toward  the  peristome. 

The  apical  system  is  large  and  compact,  the  elongated  genital  plates  giving  it  a  star-shaped 
appearance.  The  well-defined  ocular  plates,  wedged  into  the  interspaces,  make  the  entire  out- 
line subpentagonal.  Each  genital  plate  is  angular  at  the  outer  extremity  and  perforated.  On 
the  inner  edge  of  the  same  there  is  a  semicircular  depression,  in  the  center  of  wliich  is  a  small 
mammillated  tubercle. 

Tlie  peristome  is  large,  covering  quite  one-half  the  diameter  of  the  base.  It  is  divided  into 
ten  lobes  by  ten  shallow  incisions. 

Related  forms. — The  species  shows  many  points  of  similarity  to  Echinus  pafagonensis, 
described  by  D'Orbigny  in  1842,  from  the  Tertiary  of  southern  Patagonia.  The  margin  of 
D'Orbigny's  species  is  sharper  and  its  apical  system  of  somewhat  diiferent  shape;  moreover,  if 
properly  referred  to  the  Tertiar}^,  it  is  undoubtedly  a  different  form.  Echinus  andinus,  from  the 
desert  of  Atacama,  described  by  PliiUppi  in  1860,  is  likewise  closely  alhed  to6r.  zitteli,  although 
more  conical  and  presenting  a  different  surface  decoration  of  the  plates.  Goniopygus  major, 
from  the  Cenomanian  of  Europe,  is  similar  in  many  particulars,  although  the  pores  are  not 
increased  around  its  peristome  as  in  G.  zitteli,  and  its  apical  system  is  more  compact. 

Locality. — Round  Rock  (type)  and  Spanish  Oak  branch,  Williamson  County,  Tex. 

Geologic  horizon. — Edwards  hmestone  of  Fredericksburg  group,  Comanche  series,  Cretaceous. 

Collections. — U.  S.  National  Museum  (122.34);  Texas  Geological  Survey. 

Genus  LEPTARBACIA  Clark,  n.  gen. 

Test  small,  circular  in  ambital  outUne,  subhemispherical,  upper  surface  depressed,  lower 
surface  flat.  Ambulacral  plates  are  simple  primaries  near  the  apical  system  and  compound  at 
the  ambitus.  Compound  plates  consist  largely  of  one  primary  and  three  demiplates,  two  above 
and  one  below.  Interambulacra  with  large  plates  and  with  six  rows  of  small  perforated  and 
crenulated  tubercles  on  lower  surface  which  become  reduced.  Peristome  of  medium  size. 
Periproct  small. 

Leptarbacia  ARGUTtTs  Clark,  n.  sp. 

Plate  XVI,  figures  la-f. 

Determinative  characters. — Test  small,  depressed  above,  flat  below,  apical  system  of  medium 
size,  periproct  nearly  circular.  Ambulacra  straight,  rather  wide  at  ambitus  and  on  lower  sur- 
face, plates  compound  except  near  apical  system,  generally  composed  of  one  primary  and  three 
demiplates,  some  plates  with  one  primary  and  two  demiplates.  Interambulacra  with  long  bare 
median  areas  on  upper  surface,  approaching  ambitus,  and  on  lower  surface  six  rows  of  small  per- 
forated and  crenulated  tubercles. 

Dimensions. — Diameter  20  niilUmeters ;  height  12  millimeters. 

Description. — The  single  specimen  of  this  species  is  small,  with  depressed  uppev  surface 
and  nearly  flat  below.     It  is  somewhat  depressed  near  the- peristome. 

Tlie  ambulacra  are  narrow,  increasing  in  width  from  the  apical  system  to  the  ambitus, 
beyond  which  they  decrease  in  width  toward  the  peristome.  Tliere  is  a  double  row  of  about 
thirty  tubercles  in  each  area,  which  become  quite  indistinct  toward  the  apical  disk.  The  pores 
are  arranged  in  an  irregular  simple  series  in  each  poriferous  zone. 

The  interambulacra  are  about  three  times  the  width  of  the  ambulacra,  and  each  contains 
from  the  ambitus  to  the  peristome  six  rows  of  small  perforated  and  crenulated  tubercles,  the 
central  row  of  tubercles  of  each  haU  continuing  to  the  apical  system,  although  gradually  becoming 
less  distinct  as  the  latter  is  -ipproached.     The  mihary  space  is  covered  with  small  granules. 

The  apical  system  is  small,  the  genital  plates  being  somewhat  larger  than  the  ocular,  but 
rarely  projecting  farther  than  the  latter.     The  pefiproct  is  small  and  shghtly  subcentral. 

Tlie  peristome  is  apparently  of  mecUum  size  but  is  not  well  enough  preserved  to  show  its 
characteristic  features. 

Locality. — Fort  Worth,  Tex. 

Geologic  horizon. — Wasliita  group  of  the  Comanche  series,  Cretaceous. 

Collection. — Johns  Hopkins  University  (T  .3004). 


54  MESOZOIC   AND   CENOZOIC   ECHINODERMATA    OF    THE    UNITED    STATES. 

Suborder  DIADEMINA. 
Family  ORTHOPSIDiE. 

Genus  OBTHOPSIS  Cotteau. 
Oethopsis  planulata  Clark,  n.  sp. 

Plate  XVI,  figures  2a-c. 

Determinative  characters. — Test  small,  depressed,  circular  in  ambital  outline,  upper  surface 
flattened,  lower  surface  concave.  Ambulacra  narrow,  pore  pairs  simple,  primarj'  tubercles 
small.  Interambulacra  broad,  with  several  rows  of  vertical  primarj'  tubercles  sUghtty  larger 
than  the  ambulacra.     Peristome  of  medium  size. 

Dimensions. — Diameter  28  to  32  milhmeters;  height  10  to  12  millimeters. 

Descn-ption. — The  species  is  represented  by  two  specimens  embedded  in  a  single  mass  of 
indurated  marl,  one  showing  the  adoral  and  the  other  the  aboral  surface,  the  former  containing 
a  number  of  spines.  Tlie  test  is  relatively  small,  much  depressed,  the  upper  surface  being  dis- 
tinctly flat,  except  directly  at  the  apical  sj^stem,  which  is  slightly  elevated.  The  under  surface 
is  concave.  Tlie  ambulacra  are  narrow  and  bear  two  rows  of  small  perforate,  rmcrenulated 
tubercles  that  become  indistinct  toward  the  apical  system.  The  plates  are  simple  primaries  on 
the  upper  surface,  but  from  just  above  the  ambitus  to  the  peristome  two  of  the  primaries  com- 
monly combine,  the  suture  passing  through  the  interporiferous  tubercle.  Tlie  poriferous  zones 
bear  a  straight  uniserial  series  of  pores. 

The  interambulacra  are  broad,  with  six  rows  of  perforr.te,  uncrenulated  tubercles  on  the 
under  surface  which  are  much  reduced  on  the  upper  surface. 

Tlie  peristome  is  of  moderate  size. 

Locality. — Cut  on  Bonham  road,  southeastern  edge  of  Denison,  Tex. 

Geologic  Jiorizon. — Grayson  marl  member  of  the  Denison  formation,  of  Washita  group, 
Comanche  series.  Cretaceous. 

Collection. — ^Johns  Hoplcins  University  (T  3005). 

Orthopsis  occidentalis  Cragin. 
Plate  X'V'n,  figures  la-g. 

Orthopsis  occidentalis  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  pp.  160,  161,  Pis.  XXV,  figs.  1-3;  XXVII, 
fig.  2. 

Determinative  characters. — Test  large,  depressed,  slightly  pentagonal  in  ambital  outline, 
upper  surface  tumid,  lower  surface  concave ;  five  perforated  genitals,  one  a  large  madi-eporite, 
some  of  the  oculars  reaching  the  periproctal  margin.  Ambulacra  narrow,  straight;  pore  pairs 
in  simple,  straight  series ;  primary  tubercles  small,  perforate,  and  smooth ;  interambulacra  broad 
with  several  vertical  rows  of  small  primary  tubercles  similar  to  the  ambulacra.  Peristome  of 
medium  size. 

Dimensions. — Diameter  57  millimeters;  height  33  millimeters. 

Description. — Tlie  test  is  large,  somewhat  depressed,  and  slightly  pentagonal  in  ambital 
outline.  The  upper  surface  is  tumid  directlj^  above  the  ambitus,  while  the  lower  surface  is  con- 
cave. 

The  ambulacra  are  very  narrow.  Two  rows  of  small  primary  perforated  and  uncrenulated 
tubercles  extend  from  the  peristome  to  the  apical  disk.  Tlie  plates  are  simple  primaries  on  the 
upper  surface,  but  from  the  ambitus  to  the  peristome  two  of  the  primaries  generally  combine,  the 
suture  passing  through  the  interporiferous  tubercle.  The  pores  occur  in  simple  series  in  the 
narrow  poriferous  zones.  . 

Tlie  interambulacra  are  much  broader  than  the  ambulacra,  with  six  rows  of  primary  tubercles 
similar  to  those  in  the  ambulacra.  All  of  the  tubercles  about  equal  in  size  below  the  ambitus 
but  all  except  the  middle  series  of  each  row  of  plates  gradually  disappear  above  the  ambitus,  the 
latter  alone  continuing  to  the  apical  disk. 


CRETACEOUS   ECHINODEKMATA.  55 

The  peristome  is  of  medium  size  with  moderately  developed  incisions.     The  periproct  is 
relatively  large,  the  plates  of  the  apical  sj^stem  being  narrow. 
Locality. — Sierra  Blanca  Mountain,  near  El  Paso,  Tex. 
Geologic  Tiorizon. — Washita  group  of  the  Comanche  series.  Cretaceous. 
Collection.- — Geological  Survey  of  Texas. 

Family  DIADEMATID^. 

Genus  PSEUDODIADEMA  Desor. 

PSEUDODIADEMA    TEXANUM    (Rocmer). 

Plate  XVIII,  figures  la-i. 

Diadema  texanum  Roemer,  1852,  Die  Kreidebildungen  von  Texas,  p.  82,  PI.  X,  fig.  5. 

Pseudodiadema  texanum  Desor,  18.58,  Sj'uopsis  des  echinides  fossiles,  p.  72. 

Diadema  texanum  Gabb,  1859,  Catalogue  of  invertebrate  fossils  of  the  Cretaceous  formation,  p.  19. 

Pseudodiadema  texanum  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 

Pseudodiadema  roemeri  Clai'k,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 

Pseudodiadema  texanum  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 

Pseudodiadema  texanum  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  47,  48,  Pis.  XIII,  figs.  2a-n;  XIV,  figs.  la-g.      • 

Pseudodiadema  texanum  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  pj5.  161,  162. 

Pseudodiadema  texanum  Hill  and  Vaughan,  1898,  U.  S.  Geol.  Survey  Eighteenth  Ann.  Rept.,  pt.  2,  PI.  LIII,  figs.  3a,  3b. 

Pseudodiademxi  texanumBiU,  1901,  U.  S.  Geol.  Siu-vey  Twenty-first  Ann.  Rept.,  pt.  7,  PI.  XXVII,  figs.  3a,  3b. 

Determinative  cTiaracters. — Test  small,  circular,  depressed;  sides  inflated;  upper  and  lower 
surfaces  about  equally  flattened.  Ambulacra  narrow,  with  two  rows  of  primary  tubercles,  11 
or  12  in  each  row;  poriferous  zones  narrow,  pores  uniserial.  Interambulacra  mde,  with 
two  rows  of  primary  tubercles  of  larger  size  than  those  of  the  ambulacra.  Peristome  wide,  cov- 
ering nearly  one-half  the  diameter  of  the  test.  Periproct  subcircular,  with  deep  incision  in  right 
anterior  ambulacrum. 

Dimensions. — -Diameter  5  to  12  millimeters;  height  8  to  22  millimeters. 

Description. — Tliis  form,  described  by  Roemer  in  1S52  as  Diadema  texanum,  was  properly 
assigned  by  Desor  to  the  genus  Pseudodiadema. 

The  test  is  circular,  very  much  depressed  on  both  the  upper  and  lower  surfaces  and  inflated 
at  the  sides. 

The  ambulacra  are  narrow  and  lanceolate.  They  bear  two  rows  of  tubercles,  11  or 
12  in  each  row,  that  decrease  rapidly  in  size  from  the  ambitus  to  the  poles.  Tlie  areolas  are 
circular,  the  bosses  stout  and  jarominent,  the  mamelons  distinctlj-  jjerforated.  Small  secondary 
tubercles  are  irregularly  dispersed  between  the  rows  of  primary  tubercles.  A  few  scattered 
granules  surround  the  same.  The  poriferous  zones  are  uniserial  throughout,  though  the  pores 
show  a  slight  tendency  to  increase  at  the  peristome. 

The  interambulacra  are  about  twice  the  width  of  the  ambulacra.  There  are  two  rows  of 
primary  tubercles,  9  or  10  in  each  row,  that  decrease  in  size  from  the  ambitus  to  the  poles. 
The  areolas  are  depressed,  circular,  and  distinctly  outlined,  the  bosses  elevated  and  deeply  crenu- 
lated,  the  mamelons  large  and  deeply  perforated.  Small  secondary  tubercles  surromid  the  pri- 
mary tubercles,  between  which  are  interspersed  minute  granules. 

The  peristome  is  wide,  covering  nearly  one-half  of  the  diameter  of  the  test.  Ten  mcisions 
produce  well-defined  lobes  at  regular  intervals.  The  periproct  is  large  and  subcircular,  with  a 
deep  incision  in  the  right  anterior  ambulacium. 

■Related  forms. — Both  Roemer  and  Desor  mention  the  similarity  of  this  species  to  P.  tenue, 
of  the  Cenomanian  of  Europe,  from  which,  however,  it  is  separated  by  its  smaller  tubercles  and 
more  numerous  granules. 

Localities. — -Near  Fredericksburg  and  in  San  Saba  Valley  (type),  Barton  Creek  between  Oat- 
manville  and  Bee  Caves  (figured  specimen),  near  Austin  and  many  other  places  in  Texas. 

Geologic  horizon. ^Glen  Rose  limestone  of  Trinity  group  and  Comanche  Peak  limestone  of 
Fredericksburg  group,  Comanche  series,  Cretaceous. 

Collections.— \].  S.  National  Museum  (31197);  Johns  Hopkins  University. 


66  MESOZOIC   AND   CENOZOIC   ECHINODEKMATA    OF    THE    UNITED    STATES. 

PSEUDODIADEMA    DIATRETUM    (MortOIl). 

Plate  XIX,  figures  la-f. 

Cidaris  diatretum  Morton,  1833,  Am.  Jour.  Sci.,  1st  ser.,  vol.  23,  p.  294. 

Cidarites  diatretum  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  75,  PI.  X,  fig.  10. 
Cidaris  diatretum  Bronn,  1848,  Index  palaeontologicus,  vol.  1,  p.  298. 
Pseudodiadema  diatretum  Desor,  1858,  Synopsis  des  ^chinides  fossiles,  p.  73. 
Cidaris  diatretum  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  18. 
Pseudodiadema  diatretum  Cotteau,  1862-1867,  Paleontologie  franfaise,  vol.  7,  p.  519. 
Pseudodiadema  diatretum  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 
Pseudodiadema  diatretum  Conrad,  1868,  Geology  of  New  Jersey,  appendix,  p.  722. 
Cidaris  clavigera  Credner,  1870,  Deutsche  geol.  Gesell.  Zeitschr.,  vol.  22,  p.  218. 
Cidaris  sceptrifera  Credner,  1870,  Deutsche  geol.  Gesell.  Zeitschr.,  vol.  22,  p.  218. 
Pseudodiadema  diatretum  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 
Pseudodiadema  diatretum  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Pseudodiadema  diatretum  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  46,  47,  PI.  XIII,  figs.  la-f. 
Pseudodiadema  diatretum  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  6. 

Pseudodiadema  diatretum  Weller,  1907,  Cretaceous  paleontology  of  New  Jensey:  Geol.  Survey  New  Jersey,  pp.  285-286, 
PI.  IX,  figs.  1-6. 

Determinative  characters. — -Test  circular,  convex  below,  sides  inflated.  Ambulacra  wide^^ 
sinuous,  with  two  rows  of  tubercles  that  are  large  at  the  ambitus  and  decrease  toward  the  poles; 
primary  tubercles  and  several  irregular  rows  of  secondary  tubercles.  Peristome  narrow,  about 
one-third  the  diameter  of  the  test. 

Dimensions. — Diameter  30  to  .37  millimeters;  height  12.5  to  15  millimeters. 

Description. — The  specimens  vary  greatly  in  size,  the  full-grown  forms  being  moderately 
large.     The  sides  are  inflated. 

The  ambulacra  are  wide,  slightly  raised,  and  furnished  ^vith  two  rows  of  tubercles,  thirteen 
to  fourteen  in  each  row.  They  are  large  and  prominent  at  the  ambitus  but  decrease  gi-aduaUy 
toward  the  poles.  The  broad  areolas,  that  are  sharply  depressed  in  their  marginal  portions,  are 
striated  by  faint  radial  ridges  on  the  outer  parts.  At  the  upper  and  inner  angle  of  each  plate  is 
a  smaU  secondary  tubercle,  while  irregidarly  scattered  over  the  other  portions  of  the  plat«s  are 
smaller  tubercles,  and  between  them  minute  granules.  The  poriferous  zones  are  slightly  flexed, 
the  pores  of  each  plate  being  disposed  in  curved  form  about  the  margin.  Although  there  are 
generally  three  pairs  of  pores  at  each  plate,  four  pairs  are  not  infrequent  near  the  ambitus. 

The  interambulacra  are  about  one  and  one-half  times  the  width  of  the  ambulacra,  and  have 
two  rows  of  tubercles  somewhat  larger  than  those  of  the  latter.  There  are,  in  addition,  several 
irregular  rows  of  secondary  tubercles,  of  various  sizes,  that  are  most  numerous  between  the  rows 
of  primary  tubercles  and  the  poriferous  zones.  Sparsely  scattered  over  the  interambulacral 
space  are  flattened  granules. 

The  primary  tubercles  of  both  the  ambulacra  and  interambulacra  have  wide  circular  areolas, 
elevated  and  deeply  crenulated  bosses,  and  distinctly  perforated  mamelons. 

The  peristome  is  narrow,  reaching  scarcely  one-third  the  diameter  of  the  test.  The  incisions 
of  the  margin  are  weak. 

The  discal  opening  is  subpentagonal. 

Related  forms. — Tliis  species  resembles  in  some  particulars  Pseudodiadema  ornatxim  Goldfuss 
of  the  Cretaceous  of  Europe,  but  the  latter  form  has  a  different  arrangement  of  the  secondary 
tubercles  and  granules  and  lacks  the  radial  striation  upon  the  areolas. 

Localities. — Gloucester  (type).  Timber  Creek,  and  Vincentown,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group.  Upper  Cretaceous. 

Collections. — Academy  of  Natural  Sciences  of  Philadelphia  (1471);  New  Jersey  Geological 
Survey;  American  Museum  of  Natural  History,  New  York. 

Genus  HETERODIADEMA  Cotteau. 

Heterodiadema  ornatum  Clark,  n.  sp. 
Plate  XVIII,  figures  2a-f. 
Determinative  characters. — Test  small,  subconical,  ambitus  tumid,  aboral  surface  depressed, 
lower  surface  convex;  apical  opening  large;  ambulacral  plates  with  two  vertical  rows  of  small 


CRETACEOUS  ECHINODEEMATA.  57 

perforated  and  crenulated  tubercles,  pore  pairs  in  simple  series  doubling  toward  the  peristome; 
interambulacral  plates  with  two  rows  of  ])rimary  tubercles  but  slightly  larger  than  the  ambu- 
lacral.     Peristome  small. 

Dimensions. — Diameter  23  millimetere ;  height  11.5  millimeters. 

Description. — The  single  specimen  representing  this  species  is  small,  subcorneal,  depressed 
on  the  aboral  surface  but  tumid  at  the  ambitus.  It  is  apparently  distinctly  convex  on  the 
adoral  surface. 

The  ambulacra  are  moderately  narrow,  with  two  rows  of  small,  primary,  perforate,  and 
crenulate  tubercles.  The  pore  pairs  when  seen  are  simple.  The  plates  are  compound,  the 
sutures  being  very  indistinct. 

The  interambulacra  are  much  wider  than  the  ambulacra  and  bear  two  rows  of  primary 
tubercles  which  are  similar  to  the  ambulacral.  The  posterior  interambulacrum  is  deeply  incised 
and  depressed  near  the  apical  system  which  intrudes  far  into  it. 

The  large  aboral  scar  indicates  an  apical  system  of  considerable  size. 

Locality.— Fort  Worth,  Tex. 

Geologic  horizon. — Washita  group  of  the  Comanche  series,  Cretaceous. 

Collection. — Johns  Hopkins  University  (T  3006). 

Genus  COTTALDIA  Desor. 

CoTTALDiA  KOTULA  Clark,  n.  sp. 
Plate  XX,  figiires  la-d. 

Determinative  characters. — Test  small,  tumid,  subhemispherical,  aboral  and  adoral  surfaces 
somewhat  depressed;  apical  system  small;  ambulacral  plates  crowded  with  irregular  rows  of 
small  primary  tubercles,  perforate  and  noncrenulate,  pore  pairs  in  simple  series.  Interambula- 
cral plates  with  numerous  small  irregularly  disposed  tubercles ;  peristome  small. 

Dimensions. — Diameter  15  mUlimeters;  height  12.5  millimeters. 

Description. — The  test  is  small,  much  inflated  at  the  ambitus,  subhemispherical.  The 
aboral  surface  is  sHghtly  depressed  and  the  adoral  surface  more  so. 

The  ambulacra  are  narrow,  with  four  rows  of  very  small,  perforate,  and  uncrenulate  tuber- 
cles at  the  ambitus.  The  narrow  poriferous  zones  are  luiiserial.  The  compound  plates  are 
composed  of  three  primary  plates  with  very  indistinct  sutures. 

The  interambulacra  are  wide,  the  plates  being  low  and  slightly  l^ent.  A  row  of  seven  small 
tubercles  crosses  each  plate  nearly  horizontally  at  the  ambitus  but  becomes  reduced  in  number 
toward  the  poles.     These  tubercles  are  similar  in  character  to  those  on  the  ambulacra. 

The  apical  system  and  peristome  are  not  pi-eserved  on  the  specmiens  examined. 

Locality. — Shoal  Creek,  Travis  County,  Tex. 

Geologic  horizon. — Buda  (Shoal  Creek)  limestone  of  the  Washita  group,  Comanche  series, 
Cretaceous. 

Collection. — Johns  Hopkins  University  (T  3007) ;  U.  S.  National  Museum. 

Genus  HEMIPEDINA  Wright. 
Hemipedina  charltoni  Cragin. 
Hemipedina  charltoni  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  6,  pp.  41,  47,  50,  51. 

Description. — Cragin  describes  this  species  as  follows: 

Test  small,  round-pentagonal,  arched  above,  concave  below;  apical  disk  and  periproct  moderately  broad;  peris- 
tome considerably  smaller  in  proportion  to  the  test  than  in  Pscudodiadema  tc.canum  Roemer;  pore-belts  straight,  the  pcjres 
somewhat  elongated  in  the  direction  of  the  belt,  the  p(5re  pairs  simple  throughout  and  somewhat  oblique;  ambulacral 
areae  half  as  broad  as  the  interambulacral,  each  ornamented  with  two  rows  of  primary  tubercles  that  are  somewhat 
smaller  than  those  of  the  row  of  largest  tubercles  on  the  interambulacral  arese,  each  primary  tubercle  being  subtended 
by  an  irregularly  polygonal  string  of  smaller  (secondary)  ones;  interambulacral  areae  with  six  rows  of  primary  tubercles, 
these  being  much  larger  in  the  middle  row  of  each  semiambulaci-um  than  in  the  others,  the  primaries  subtended  by 
secondaries  for  the  most  part  in  polygonal  strings;  surface  of  test  closely  granulated  in  the  intervals  between  tubercles 
oa  both  ambulacral  and  interambulacral  arese. 


58  MESOZOIC   AKD    CENOZOIC    ECHINODEEMATA    OF    THE    I'XITED    STATES. 

No  figures  are  given  and  tlie  incompleteness  of  tlie  description  leave  some  question  as  to 
whether  the  reference  of  this  form  to  Hemipedina  is  correct. 

Dimensions. — Diameter  25  millimeters;  height  11  millimetei-s ;  width  of  peristome  7  to  8 
millimeters;  width  of  periproct  3.5  millimeters. 

Locality. — About  a  mile  east  of  Denison,  Grayson  Countj-,  Tex. 

Geologic  horizon. — ^Main  Street  limestone  member  of  the  Denison  formation  of  Washita 
group,  Comanche  series,  Cretaceous. 

Collection. — Baylor  Univei-sit}^. 

Family  DIPLOPODIID.E. 

Genus  DIPLOPODIA  McCoy. 

DiPLOPODIA    TAFFI    CrEgUl. 

Plate  XX,  figures  2a-e. 

Diplopodia  taffi  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Kept.,  pp.  148,  149,  PI.  XLVI,  fig.  3. 

Determinative  characters. — Test  large,  subcircular,  depressed;  lower  surface  flattened; 
ambulacra  with  two  vertical  rows  of  primary  tubercles  perforate  and  crenulate,  slightly  smaller 
than  the  interambulacral  tubercles,  pairs  of  pores  biserial  above  the  ambitus  toward  the  apical 
system  and  at  the  peristome,  iniserial  below  the  ambitus;  interambulacral  plate  with  eight  rows 
of  primary  tubercles  at  the  ambitus;  peristome  small  with  well-marked  incisions. 

Dimensions. — Diameter  59  millimeters;  height  26  millimeters. 

Description. — This  verj^  beautiful  species  is  one  of  the  largest  in  the  Lower  Cretaceous.  It 
is  represented  by  a  number  of  specimens  although  far  less  common  than  CypJiosoma  texanum,  with 
which  it  is  found  associated. 

The  test  is  depressed  and  shghtly  pentagonal  in  outline.  The  lower  sm^ace  is  flattened, 
the  sides  somewhat  inflated,  and  the  upper  surface  slightly  elevated. 

The  ambulacra  are  of  moderate  width,  -with  two  vertical  rows  of  perforate  and  crenulate 
primary  tubercles,  which  are  slightly  smaller  than  the  interambulacral  tubercles.  The  pore 
pairs  are  biserial  from  the  ambitus  above  toward  the  apical  system  and  at  the  peristome,  but 
uniserial  from  the  ambitus  toward  the  peristome. 

The  interambulacra  are  broad,  with  sLx  rows  of  large  and  two  of  small  primary  tubercles  at 
the  ambitus,  the  small  tubercles,  one  row  on  each  side  outside  the  large  tubercles,  being  confined 
to  that  region.  The  outer  rows  of  large  tubercles  likewise  do  not  reach  the  peristome  and  apical 
system.     A  broad  and  somewhat  depressed  area  follows  the  median  section  of  the  ambulacra. 

The  apical  system  is  not  large  and  its  rays  penetrate  deeply  the  interambulacra. 

The  peristome  is  small,  with  ten  rather  deep  branchial  incisions. 

Related  forms. — This  species  shows  some  similarity  to  D.  streeruvitzi,  but  is  not  quite  as 
much  elevated  aborally. 

Localities. — North  San  Gabriel  River,  3  mUes  above  Georgetown  (typo),  Benbrook,  Tarrant 
County,  and  Blum,  Hill  County,  Tex. 

Geologic  Jionzon. — Comanche  Peak  limestone  of  Fredericksburg  group,  Comanche  series, 
Cretaceous. 

Collections. — Geological  Survey  of  Texas;  U.  S.  National  Museum. 

Diplopodia  streeruvitzi  Cragin. 

Plate  XX,  figures  3a-c. 

Diplopodia  strra-uvitzi  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Kept.,  pp.  147,  148.  PL  XXIV,  fig.  11,  Pl.  XXV, 
figs.  9-10. 

Determinative  characters. — Test  medium  size,  subcircular,  depressed,  upper  and  lower  sur- 
faces flattened;  ambulacral  plates  with  two  vertical  rows  of  primary  tubercles,  pairs  of  pores 
simple  except  toward  apical  system  and  peristome  where  the}'  are  biserial ;  interambulacral  plates 
with  six  to  eight  vertical  rows  of  primary  tubercles  at  the  ambitus ;  peristome  small. 

Dimensions. — Diameter  25  to  50  millimeters;  height  12  to  IS  millimeters. 


CRETACEOUS   ECHINODERMATA.  59 

Description. — This  species  is  not  numerous,  and  the  loiown  forms  are  confined  to  El  Paso 
County,  Tex.  The  test  is  very  nearly  circidar  m  ambital  outline,  is  depressed,  and  is  distinctly 
flattened  both  adorally  and  aborally. 

The  ambulacra  are  of  moderate  width  with  two  vertical  rows  of  perforate  and  crenulate 
primary  tubercles  of  about  the  same  size  as  the  interambidacral  tubercles.  The  poriferous  zones 
are  wide  above  the  ambitus  but  narrow  at  the  ambitus  and  below  until  near  the  peristome.  The 
pore  pairs  are  biserial  aborally.     There  is  much  crowding  of  the  pore  pairs  at  the  peristome. 

The  interambidacra  are  wide  with  six  or  eight  rows  of  primary  tubercles  similar  to  those  of 
the  ambulacra.  The  outer  rows  are  somewhat  irregular  in  distribution  and  gradually  disappear 
aborally. 

The  apical  system  is  of  medium  size.     The  peristome  is  small. 

Localities. — Sierra  Blanca  peaks  (type)  and  near  Kent,  El  Paso  County,  Tex. 

Geologic  liorlzon. — Washita  group  of  the  Comanche  series,  Cretaceous. 

Collections. — Geological  Survey  of  Texas;  U.  S.  National  Museum. 

Family  CYPHOSOMATID^. 

Genus  CYPHOSOMA  Agassiz. 

Cyphosoma  hilli  Clark. 

Plate  XIX,  figures  2a-g. 

PscudodiadcmahilliClark,  1801,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Diplopodia  hilli  Clark,  1803,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103.  p.  51. 
Diplopodia  hilli  Clark,  1893,  U.  S..  Geol.  Survey  Bull.  97,  pp.  .50,  51,  PI.  XVI,  figs.  2a-g. 
Diplopodia  hilli  Cragin,  1893,  Geol.  Survey  Texas  Foiuth  Ann.  Rept.,  p.  147. 

Determinative  characters. — Test  subpentagonal,  depressed;  sides  inflated;  upper  and  lower 
sm"faces  flattened.  Ambidacra  prominent,  straight,  with  two  rows  of  primary  tubercles,  twelve 
or  thirteen  in  each  row;  poriferous  zones  narrow,  with  slight  increase  in  width  toward  the  ajoical 
system ;  pores  in  single  pairs  below  but  biserial  on  the  upper  surface.  Interambulacra  with  two 
rows  of  primary  tubercles  of  equal  size  with  those  of  the  ambulacra.  Peristome  narrow,  circular. 
Discal  opening  broad,  pentagonal. 

Dimensions. — Diameter  20  miUimeters;  height  8  millimeters. 

Description. — The  test  has  a  subpentagonal  outliiie,  the  projecting  ambulacra  occupying  the 
angles.  It  is  depressed  on  both  the  upper  and  lower  surfaces,  the  latter  becoming  somewhat 
concave  toward  the  peristome.     The  sides  are  moderately  inflated. 

The  ambulacra  are  broad,  very  prominent,  and  furnished  with  two  rows  of  large  tubercles, 
twelve  or  thu-teen  in  each  row,  that  decrease  rapidly  from  the  ambitus  toward  the  apical  system 
and  peristome.  Tlie  poriferous  zones  are  narrow  and  lanceolate.  The  pores  are  arranged  in 
single  pairs  on  the  lower  surface,  but  from  the  ambitus  to  the  apical  system  are  increased  slightly 
in  number,  and  near  the  apical  system  become  biserial.  The  interambidacra  are  narrow  and 
appear  flattened  as  compared  with  the  slightly  projecting  ambidacra.  They  are  provided  with 
two  rows  of  primary  tubercles  of  ecjual  size  with  those  of  the  ambidacra.  There  are  ten  or  eleven 
in  each  row.  The  areolas  are  narrow,  circular,  and  elevated,  the  bosses  prominent  and  distinctly 
crenulated,  and  the  mamelons  deeply  perforated.  The  tubercles  are  somewhat  widely  separated 
and  the  intervening  space  is  covered  with  small  secondary  tubercles  and  sparsely  scattered 
granules. 

The  peristome  is  broad,  depressed,  and  circular.  It  is  divided  by  ten  incisions  mto  well- 
defined  lobes,  those  of  the  ambulacra  laroader  and  extending  farther  into  the  opening  than  the 
others. 

The  discal  opening  is  pentagonal,  the  angles  occm-ring  at  the  point  of  the  medial  suture  of 
the  interambulacra. 

This  species  which  was  earlier  referred  to  Diplopodia  has  been  shown  to  belong  to  the  genus 
Cyphosoma.  Better  material  has  furnished  specimens  in  which  the  morphology  of  the  ambulacra 
demiplates  can  be  clearly  seen. 


60  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA    OF    THE    UNITED    STATES. 

Related  forms. — Tho  species  is  not  unlike  C.  texcmum,  from  wliich,  however,  it  is  separated  by 
its  smaller  size,  subpentagonal  form,  and  two  instead  of  four  rows  of  primary  tubercles. 
Locality. — ^Austin,  Tex. 

Geologic  horizon. — Austin  chalk,  Upper  Cretaceous. 
Collections. — U.  S.  National  Museum  (S311);  Johns  Hopkins  University. 

CypHosoMA  TEXANUM  Roemep. 

Plate  XXI,  figures  la-g. 

Diadema  texanum  Roemer,  1849,  Texas,  p.  392. 

Cyphosoma  texanum  Roemer,  1852,  Die  Kreidebildungen  von  Texas,  p.  82,  PI.  X,  fig.  6. 

Cijphosoma  texanum  Conrad,  1857,  in  Hall's  U.  S.  and  Mex.  Boundary  Survey  Rept.,  vol.  i,  pt.  2,  p.  145,  PI.  I,  fig.  3. 

Phym.osoma  texanum  Desor,  1858,  Synopsis  des  6chinides  fossiles,  p.  90. 

Cyphosoma  texanum  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  18. 

Cyphosoma  texanum  Gabb,  1869,  Geol.  Survey  California,  Paleontology,  vol.  2,  p.  276. 

Pseudodiadema  texanum  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  75. 

Diplopodia  texanum  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 

Diplopodia  texanum  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  47,  48,  PI.  XV,  figs,  la-f;  PI.  XVI,  figs.  la-d. 

Cyphosoma  texana  Aguilera,  1893,  Datos  para  la  geologia  de  Mexico,  p.  26. 

Diplopodia  texana  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  149. 

Diplopodia  texanum  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  5,  p.  47. 

Cyphosoma  texana  Aguilera,  1897,  Inst.  geol.  Mexico  Bol.,  Nos.  4,  5,  and  6,  p.  21. 

Diadema  texana  Bose,  1899,  Inst.  geol.  Mexico  Bol.,  No.  13,  p.  11. 

Cyphosoma  texana  Bose,  1899,  Inst.  geol.  Mexico  Bol.,  No.  13,  p.  11. 

Determinative  cTmracters. — Test  large,  subcircular;  sides  inflated;  upper  surface  elevated; 
lower  surface  depressed,  concave.  Ambulacra  promment,  with  two  rows  of  primary  tubercles; 
poriferous  zones  broad  above,  narrow  below;  pores  uniserial  from  near  peristome  to  ambitus, 
beyond  which  to  the  apical  system  they  are  biserial.  Interambulacra  wide,  with  four  rows  of 
primary  tubercles  at  the  ambitus,  which  become  reduced  to  two  at  the  pores.  Peristome  wide, 
about  two-fifths  the  diameter  of  the  test.     Periproct  large,  subpentagonal. 

Dimensions. — Diameter  15  to  20  millimeters;  height  8  to  20  millimeters. 

Description. — This  species  was  first  described  by  Eoemer  m  1849  as  Diadema  texanum,  but 
subsequently,  in  1852,  was  referred  to  Cyphosoma. 

The  test  is  large,  subcircular,  and  elevated.  The  sides  are  inflated  and  the  aboral  surface 
elevated  and  convex.     The  base  is  depressed  and  concave. 

The  ambulacra  are  broad  and  lanceolate.  They  have  two  rows  of  primary  tubercles,  four- 
teen or  fifteen  in  each  series,  that  are  large  at  the  ambitus  and  decrease  gradually  toward  the 
poles.  A  circle  of  scattered  granules  surrounds  the  narrow  areolas.  The  poriferous  zones  are 
broad  upon  the  upper  surface,  but  below  the  ambitus  are  very  much  narrowed.  The  pores  are 
uniserial  below  the  ambitus  except  directly  at  the  peristome,  where  they  become  greatly  in- 
creased.    From  the  ambitus  to  the  apical  system  they  are  biserial. 

The  interambulacra  are  about  one  and  one-half  times  the  width  of  the  ambulacral  at  the 
ambitus.  There  are  four  rows  of  primary  tubercles  at  the  ambitus  which  become  reduced  to  two 
m  the  vicmity  of  the  apical  system  and  peristome.  In  the  center  of  the  column  the  tubercles  of 
the  four  rows  are  of  about  equal  size,  but  those  of  the  outer  rows  become  much  more  rapidly 
reduced  in  size  toward  the  poles.  Small  secondary  tubercles  are  found  on  the  outer  mai^in  of  the 
plates,  while  uregularly  scattered  granules  cover  the  space  between  the  tubercles.  A  slight, 
depression  occurs  along  the  line  of  the  median  suture. 

The  peristome  is  circular,  but  is  broken  by  distinct  incisions.  Its  diameter  is  about  two- 
fifths  that  of  the  test.     The  periproct  is  large  and  subpentagonal. 

The  species  was  incorrectly  referred  earlier  by  the  author  to  Diplopodia.  A  more  thorough 
study  of  the  much  better  material  now  available  shows  that  this  form  is  a  Cyphosoma. 

Related  forms. — The  species  is  verv  closely  related  to  if  not  identical  with  C.  volanum  of  tiie 
Washita  group,  but  is  somewhat  taller  and  its  four  rows  of  primary  tubercles  on  each  interam- 
bulacrum  are  rather  more  definitely  developed  even  on  small  specimens.     It  riso  shows  a  less 


CRETACEOUS  ECHINODEKMATA.  61 

subpentagonal  ambital  outline.  If  the  difl'ei'ences  are  more  than  varietal,  then  C.  texanum  must 
at  all  events  be  regarded  as  the  ancestor  of  C.  volanum. 

Localities. — Fredericksburg  and  in  the  San  Saba  River  valley  (type),  Leon  S])rings  (figured 
specimen),  near  Austin,  and  many  other  places  iia  Texas. 

Geologic  Jiorizon. — Comanche  Peak  limestone  of  Fredericksburg  group,  Comanche  series, 
Cretaceous. 

Collections. — U.  S.  National  Museum  (9S3S);  Boston  Society  of  Xatural  Historj-;  Geologi- 
cal Survey  of  Texas;  University  of  Iowa ;  Johns  Hopkins  Univei-sity. 

Ctphosoma  volanum  Cragin. 

Plate  XXI,  figures  2a-b,  3. 

Cyphosoma  volanum  Cr&gin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  147. 

Cyphosoma  volanum  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  4,  pp.  45,  47. 

Cyphosoma  volanum  HiQ.,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.-7,  p.  283. 

Determinative  cTiaracters. — Test  small,  subcircular;  upper  surface  slightly  elevated;  lower 
surface  depressed,  concave.  Ambulacra  slightly  prominent,  with  two  rows  of  prmiaiy  tubercles ; 
poriferous  zones  sinuous;  pores  uniserial  from  peristome  nearly  to  apical  sj-stem.  Inter- 
ambulacra  wide,  each  with  two  rows  of  primary  tubercles,  smiilar  to  those  of  ambulacra,  adjoin- 
ing which  are  smaller  prunary  or  secondary  tubercles.     Peristome  small.     Periproct  large. 

Dimensions. — Diameter  17.5  millimeters;  height  8  millimeters. 

Description. — This  small  species  has  a  subcii-cular  test  with  a  sliglitly  elevated  uj^per  surface. 
In  general  size  and  appearance  the  smaller  specimens  resemble  Pseudodiadema  texanum,  but 
theii-  other  characters  are  very  different. 

The  ambulacra  are  broad,  with  two  rows  of  primary  tubercles  eight  or  nine  in  each  row. 
The  tubercles  are  large  at  the  ambitus  but  become  very  small  toward  the  apical  system  and  peri- 
stome. The  poriferous  zones  are  narrow  on  the  lower  surface  and  at  the  ambitus,  but  widen  above. 
They  are  smuous.     The  pores  are  uniserial,  although  crowded  toward  the  apical  system. 

The  interambulacra  are  wide.  There  are  two  rows  of  primary  tubercles  sunilar  to  those  of 
the  ambulacra  extending  from  the  peristome  to  the  apical  system.  Additional  smaller  primary 
or  secondary  tubercles,  somewhat  irregularly  dispersed,  adjoin  the  primary  tubercles,  while 
numerous  granules  occur  on  the  surface  of  the  plates. 

The  peristome  is  small  with  distinct  branchial  incisions.  The  periproct  is  large  and  sub- 
pentagonal. 

Related  forms. — Few  if  any  differences  serve  to  separate  this  form  from  C.  texanum  of  the 
Fredericksburg  group.  In  general  it  is  lower  and  more  depressed,  is  rather  more  subpentagonal 
in  outline,  and  the  four  rows  of  tubercles  on  its  interambulacra  are  less  full}'  defined  in  many 
specimens.  If  more  than  a  variety,  it  is  certaiialy  very  closely  related  to  C.  texanum  and  de- 
scended from  it. 

Localities. — Below  the  Missouri,  Kansas  &  Texas  Railway  bridge  on  Big  Elm  Creek,  Benton 
County  (type),  and  DenLson,  Grayson  County,  Tex. 

Geologic  Jiorizon. — Denison  fonnation  of  Washita  group,  Comanche  series.  Cretaceous. 

Collection. — Geological  Survey  of  Texas  (A,  B). 

Genus  COPTOSOMA  Desor. 

CoPTOsoMA  spEciosuM  Clark. 

Plate  XIX,  figures  3a-li. 

Cyphosoma  speeiosum  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  70. 
Coptosonna  speciosum,  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  p.  51. 
Coptosoma  speciosum  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  52,  53,  PI.  XVIII,  figs.  hi-h. 
Coplosoma  speciosum  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  0. 

Pseudodiadema  speciosuvi  Weller,  1907,  Cretaceous  paleontology  of   New  Jersey:  Geol.  Sur\ey  New  Jersey,  pp.  280- 
288,  PI.  IX,  figs.  7-14. 

Determinative  cTiaracters. — Test  circular,  inflated  at  the  sitlcs,  flattenetl  on  the  upper  and 
lower  surfaces.     Ambulacra  wide,  wth  two  rows  of  primary  tubercles,  twelve  or  thirteen  in 

39800°— 15 5 


62  MESOZOIC    AND   CENOZOIC   ECHINODEEMATA    OF    THE    UNITED    STATES. 

each,  that  gradually  diminish  in  size  toward  the  poles ;  poriferous  zones  sinuous ;  pores  uniserial. 
Interambulacra  with  two  rows  of  tubercles  shghtly  larger  than  those  of  the  ambulacra.  Peri- 
stome one-third  the  diameter  of  the  test. 

Dimensions. — Diameter  17  millimeters;  height  9.5  millimeters. 

Description. — This  delicate  species  has  a  circular  test  with  inflated  sides.  Both  poles  are 
flattened,  the  lower  more  than  the  upper. 

The  ambula,cra  are  wide  and  prominent,  and  bear  two  rows  of  large  tubercles,  twelve  or 
thirteen  in  each  row.  The  areolas  are  nearly  confluent  above  and  below  and  are  striateil  by 
irregular  radiating  ridges.  The  bosses  are  deeply  crenulated,  and  the  small  mamelons  are  imper- 
forate. Minute  tubercles  and  granules  irregularly  surround  the  primary  tubercles,  occurring 
in  greatest  number  along  the  central  suture.  The  poriferous  zones  are  slightly  sinuous,  the 
three  pore  pairs  having  a  ciu-ved  arrangement  on  each  ambulacral  plate. 

The  interambulacra  are  about  one  and  one-half  times  as  wide  as  the  ambulacra.  They 
have  two  rows  of  primary  tubercles  that  are  somewhat  larger  than  those  of  the  ambulacra.  The 
areolas  are  very  large  and  are  confluent  above  and  below.  Throughout  the  greater  part  of  the 
column  the  two  rows  approach  each  other,  but  toward  the  apical  system  they  are  widely  sepa- 
rated from  one  another.  The  smaller  tubercles  are  disposed  in  rows,  with  greater  or  less  regu- 
larity, on  either  side  of  the  primary  series. 

Th'i  peristome  is  narrow,  occupying  a  little  more  than  one-third  of  the  diameter  of  the  test. 
It  has  an  irregular  pentagonal  outline.     The  discal  opening  is  large  and  pentagonal  in  form. 

Related  forms. — This  form  is  apparently  closely  related  to  C.  mortoni,  but  is  more  elevated 
and  does  not  exhibit  granules  between  the  pores. 

Locality. — Timber  Creek,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group.  Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1468). 

CoPTOSOMA  MOKTONi  (De  Loriol). 

Plate  XXII,  figures  la-e. 

Cyphosoma  mortoni  De  Loriol,  1887,  Recueil  zool.  Suisse,  vol.  4,  No.  3,  pp.  389-391,  PI.  XVII,  figs.  2a-c. 
Coptosoma  mortoni  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  pp.  51,  52,  PI.  XVII,  figs!  la-e. 

Determinative  characters. — Test  circular,  depressed.  Ambiflacra  very  wide,  with  two  rows 
of  primary  tubercles,  thirteen  in  each  row,  the  three  or  four  at  the  ambitus  large  and  nearly  con- 
fluent, but  diminishing  rapidly  in  size  toward  either  pole;  poriferous  zones  narrow,  sinuous; 
pores  uniserial,  those  of  each  pair  separated  by  a  granule.  Interambulacra  with  two  rows  of 
tubercles,  nine  or  ten  in  each  row.     Peristome  very  large. 

Dimensions. — Diameter  12-15  millimeters;  height  about  6  miUmieters. 

Description. — The  writer  has  been  unable  to  obtain  a  specimen  of  this  species,  but  the  very 
full  description  and  excellent  figm-es  given  by  De  Loriol  admit  of  its  satisfactory  identification. 
The  description  that  follows  is  largely  a  translation  of  that  given  by  De  Loriol.  The  two  speci- 
mens in  the  possession  of  De  Loriol  were  so  deformed  that  he  could  not  determine  the  height 
accurately.  The  test  is  circular  and  depressed.  The  ambulacra  are  relatively  very  wide, 
almost  as  large  as  the  interambulacra,  and  bear  two  rows  of  large  tubercles,  thirteen  in  each  row. 
The  fii'st  four  or  five  tubercles  from  the  apical  system  are  far  apart  and  very  small.  At  the 
ambitus  three  or  four  of  the  tubercles  are  very  large,  with  nearly  confluent  areolas,  but  rapidly 
diminish  in  size  toward  the  lower  surface,  the  last  foiu"  or  five  being  very  small  and  with  diffi- 
culty distinguished.  The  areolas,  except  at  the  ambitus,  are  not  large.  The  bosses  are  finely 
crenulated  and  the  mamelons  small  and  imperforate.  Upon  the  lower  surface  there  are  large 
mammillated  granules  which  can  be  with  difficulty  distinguished  from  the  primary  tubercles. 
Each  areola  is  also  partially  surrounded  by  a  circle  of  small  granules  that  occiu*  most  numer- 
ously near  the  line  of  the  central  sutm-e.  The  granules  are  few  in  number  on  the  upper  surface. 
The  poriferous  zones  are  narrow,  slightly  sinuous,  and  composed  of  small  pores  without  any 
increase  between  the  apical  system  or  peristome.  A  small  granule  is  found  between  the  jjores 
of  each  pair. 


CRETACEOUS  ECHINODEEMATA.  63 

Tlie  interambulacra  bear  two  rows  of  primary  tubercles  that  are  similar  to  those  of  the  ambu- 
lacra, but  larger  and  loss  numerous.  The  lower  surface  is  covered  by  large  mammillated  granules 
that  can  scarcely  be  distinguished  from  the  tubercles,  and  also  by  numerous  small  ones.  There 
are  few  granules  on  the  upper  surface.     The  peristome  is  large,  with  slight  incisions. 

Belated  forms. — The  species  is  most  closely  related  to  C.  speciosum,  but  in  form  and  in 
several  details  of  structure  is  unlike  it.  The  presence  of  granules  between  the  pores  of  the 
present  species  is  apparently  marked. 

Locality. — Wahalak,  Kemper  County,  Miss. 

Geologic  honzon. — Selma  chalk.  Upper  Cretaceous. 

Collection. — P.  de  Loriol,  S'vx'itzorland. 

Genus  MICBOPSIS  Cotteau. 
MicROPSis  LiNEATUs  Clark,  n.  sp. 
Plate  XXV,  figures  la-c. 

Determinative  cJiaracters. — Test  metlium  size,  slightly  polygonal  in  ambital  outline,  tumid 
above,  subhemispherical,  slightly  concave  below.  Apical  system  wanting.  Ambulacra  with 
compound  plates  covered  with  two  rows  of  primary  tubercles  perforate  and  crenulate.  Inter- 
ambulacra with  six  rows  of  primary  tubercles,  which  rapidly  decline  in  size  above  the  ambitus. 
Peristome  small. 

Dimensions. — Diameter  25.25  millimeters;  height  12  millimeters. 

Description. — The  test  is  of  mediimi  size  and  slightly  polygonal  in  ambital  outline,  with 
tumid  upper  sm-face.     It  is  subhemispherical  and  slightly  concave  on  the  lower  surface. 

The  ambulacra  are  narrow  and  covered  with  two  vertical  rows  of  perforate  and  crenulate 
primary  tubercles.  The  poriferous  zones  are  not  sharply  defined.  The  plates  are  compound, 
with  a  low  primary  adorally. 

The  interambulacra  have  sbc  rows  of  primary  tubercles  which  decline  rapidly  in  size  above 
the  ambitus. 

The  peristome  is  small  and  with  slight  branchial  incisions. 

Locality. — Cut  on  Bonham  road,  southeast  edge  of  Denison,  Tex. 

Geologic  horizon. — Grayson  marl  member  of  the  Denison  formation,  of  Washita  group, 
Comanche  series.  Cretaceous. 

Collection. — U.  S.  National  Museum  (31198). 

Suborder  ECHININA. 
Family  TRIPLECHINID.E. 

Genus  PSAMMECHINTJS  Agassiz. 

PSAMMECHINUS    CINGULATUS    Clark. 

Plate  XXII,  figm-es  2a-i. 

Psammcchinus  cingulatus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Psammechinus  cingidatus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Psammcchinus  cingulatus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  55,  PI.  XX,  figs.  la-i. 
Psammechinus  cingulatus  Johnson,  1905,  Acad.  Nat.  Sci.  Pluladelphia  Proc,  vol.  57,  p.  6. 

Psammechinus  cingulatus  Waller,   1907,   Cretaceous  paleontology  of  New  Jersey:    Geol.  Survey   New  Jersey,   pp. 
288-289,  PI.  X,  figs.  1-9. 

Determinative  characters. — -Test  small,  hemispherical,  with  circular  outhne;  sides  mflated; 
upper  surface  elevated;  base  flattened  and  concave.  Ambulacra  wide,  with  two  rows  of 
primary  tubercles,  sixteen  or  seventeen  in  each  series;  poriferous  zones  depressed,  triserial. 
Interambulacra  about  one  and  one-half  times  the  width  of  the  ambulacra;  plates  covered  with 
numerous  uncrenulatc  and  imperforate  tubercles.     Peristome  large,  with  ten  deep  incisions. 

Dimensions. — -Diameter  22  millimeters;  height  12.5  millimeters. 

Description. — This  delicate  form,  of  which  two  very  imperfect  specimens  were  examined  by 
the  writer,  is  hemispherical  in  shape,  Avith  circular  circumference,  inflated  sides,  elevated  upper 


64  MESOZOIC   AND   CENOZOIC   ECHINODEKMATA   OF    THE    UNITED    STATES. 

surface,  and  flattened  base.  In  the  vicinity  of  the  mouth  opening  the  lower  surface  is  depressed, 
producing  a  shght  concavity. 

The  ambulacra  are  wide  and  composed  of  eighteen  to  twenty  plates.  The  lower  sixteen  or 
seventeen  of  each  series  bear  prominent  tubercles  that  occur  in  a  continuous  line  to  the  peristome. 
On  cither  side  of  the  primary  tubercles  are  smaller  ones  of  like  shape.  The  three  pore  pairs  are 
arranged  in  semicircular  form,  the  two  upper  separated  from  the  lower  by  one  of  the  secondary 
tubercles. 

The  interambulacra  are  about  one  and  one-half  times  as  wide  as  the  ambulac]-a  and  the 
plates  are  about  fifteen  in  number.  Each  plate  bears  a  large  tubercle  in  the  center,  and  irregu- 
larly arranged  about  it  smaller  tubercles  of  various  sizes. 

The  peristome  is  large,  with  10  deep  incisions.  The  apical  system  is  lacking,  but  the  discal 
opening  is  large  and  pentagonal  in  form. 

Related  forms. — This  unique  species  is  quite  unlike  any  hitherto  described,  and  is  readily 
characterized  by  the  arrangement  of  the  tubercles  and  pore  pairs.  As  the  only  representative 
of  the  genus  in  American  Cretaceous  deposits  it  has  especial  interest. 

Locality. — 'Timber  Creek,  N.  J. 

Geologic  Tiorizon. — -Vincentown  sand  of  Kancocas  group,  Upper  Cretaceous. 

Collection. — ^Academy  of  Natural  Sciences  of  Philadelphia  (1467). 

Genus  PEDINOPSIS  Cotteau. 
Pedinopsis  symmetrica  (Cragin). 

Plate  XXIII,  figures  la-h. 

Dimblea  symmetrica  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  150,  PL  XXXIV,  fig.  12,  PI.  XXV,  figs. 
4-7;  PL  XXVII,  fig.  1. 

Determinative  characters. — Test  medium  size,  subcorneal,  mflated  on  the  aboral  surface,  con- 
cave on  the  adoral  surface,  sides  tumid.  Ambulacra  with  several  vertical  rows  of  primary  per- 
forate tubercles,  poriferous  zones  broad,  pore  pairs  biserial.  Interambulacra  broad  and  low 
with  many  rows  of  primary  tubercles  similar  to  those  of  the  ambulacra.  Apical  system  small, 
madreporite  large,  posterior  right-hand  ocular  reaches  the  periproct.     Peristome  small. 

Dimensions. — -Diameter  15  to  45  millimeters;  height  12  to  3.3  millimeters. 

Description. — The  species  referred  by  Cragin  to  a  new  geiaus  which  he  named  Dumblea  is 
evidently  a  representative  of  the  genus  Pedinopsis.  A  specimen  referred  to  J.  W.  Gregory  of 
Glasgow  was  pronounced  by  him  to  be  a  typical  Pedinopsis. 

The  test  is  of  medium  size,  tumid,  subcorneal,  flattened  and  concave  on  the  lower  surface. 
Tire  circular  ambital  outline  is  somewhat  broken  by  the  sutures  between  the  ambulacra  and 
interambulacra  producing  an  imperfectly  defined  15-lobed  appearance. 

The  ambulacra  are  rather  broad  with  well-defined  poriferous  zones.  They  are  covered  with 
two  rows  of  primary  tubercles  in  the  smaller  and  four  in  the  larger  specimens.  These  tubercles 
are  perforate  and  apparently  plain  or  uncrenulate,  although  the  state  of  preservation  makes  it 
uncertain  as  to  whether  delicate  crenulation  may  not  have  existed. 

The  interambulacra  are  broad  and  low  with  many  vertical  rows  of  primary  tubercles  similar 
to  those  of  the  ambulacra.     They  diminish  in  number  aborally. 

The  ajjical  system  is  small,  the  madreporite  being  large  and  encroaching  on  the  adjacent 
genitals.     The  posterior  right-hand  ocular  reaches  the  periproct. 

The  peristome  is  small  with  well-marked  branchial  incisions.     Tlie  periproct  is  oval. 

iocaHfies.— Sierra  Blanca  peaks  (type)  and  near  Kent,  El  Paso  County,  Tex. 

Geologic  Aonzon.— Washita  group  of  the  Comanche  series.  Cretaceous. 
Collections. — Geological  Survey  of  Texas;  U.  S.  National  Museum. 


CBETACEOUS  ECHINODEEMATA.  65 

Pedinopsis  pondi  Clark. 
Plate  XXIV,  figures  la-d. 

Pedinopsis  pondi  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 

Pedinopsis  pondi  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  57,  PI.  XXI,  figs,  la-b;  PL  XXII,  figs.  la-c. 

Determinative  characters. — Test  large,  circular,  inflated  at  the  sides,  convex  on  the  upper 
surface.  Ambulacra  with  six  rows  of  tubercles  at  the  ambitus,  the  two  marginal  rows  con\plete 
and  the  four  inner  incomplete;  poriferous  zones  broad,  biserial.  Interambulacra  \vith  20 
rows  of  tubercles  at  the  ambitus,  which  become  reduced  to  four  at  the  margin  of  the  peristome ; 
tubercles  small,  equal,  crenulate,  and  perforate.     Peristome  small,  with  distinct  incisions. 

Dimensions. — Diameter  88  millimeters;  height  58   millimeters. 

Description. — The  very  large  specimen  on  which  this  species  is  estabhshed  has  portions  of 
the  test  in  a  very  perfect  state  of  preservation.  The  test  is  large,  circular,  inflated  at  the  sides, 
and  convex  on  the  upper  surface.  The  lower  surface  is  flattened,  with  a  shglit  concavity  in 
the  region  of  the  peristome. 

The  ambulacra  are  wide,  and  have  at  the  ambitus  six  rows  of  tubercles,  the  two  marginal 
rows  alone  continuing  from  the  discal  opening  to  the  peristome.  The  four  inner  rows  are  incom- 
plete, but  of  equal  size  wath  the  outer.  The  tubercles  are  finely  crenulated  and  perforated.  The 
poriferous  zones  ai-e  broad  and  biserial,  except  on  the  lower  surface,  where  the  pore  pairs  become 
crowded  together.  Near  the  peristome  they  again  broaden  out  and  become  greatly  increased 
in  number  at  the  margin.     The  pores  are  small  and  round. 

The  interambulacra  are  broad  and  have  twenty  rows  of  tubercles  at  the  ambitus,  which 
become  reduced  to  four  at  the  peristome.  The  tubercles  are  of  equal  size  with  those  of  the 
ambulacra.  Small  mammillated  granules  are  found  scattered  over  both  the  ambulacral  and 
interambulacral  plates,  together  with  a  fine  granulation  covering  the  entire  surface. 

The  peristome  measures  about  seven-eighths  of  an  inch  in  diameter.  It  has  10  distinct 
incisions  in  the  interambulacra.     The  discal  opening  is  partly  outlined  but  is  very  indistinct. 

This  species  is  named  for  Edwin  J.  Pond,  of  the  United  States  Coast  and  Geodetic  Survey,. 
by  whom  the  specimen  described  by  the  writer  was  discovered. 

Locality. — The  south  bank  of  Onion  Creek,  about  one-fourth  mile  southwest  of  the  crossing; 
of  the  Austin  and  San  Antonio  wagon  road,  Travis  County,  Tex. 

Geologic  horizon. — Austin  chalk,  Upper  Cretaceous. 

Collection. — Johns  Hopkins  University  (T  .3008).  ,  ' 

Subclass  IRREGLTI.ARIA. 

Order  GNATHOSTOMATA, 

Suborder  HOLECTYPINA. 

Family  PYGASTERID.E. 

Genus  HOLECTYPXTS  Desor. 
HoLECTYPUs  PLANATUS  Roemer. 

Plate  XXV,  figures  2a-f,  3a-c,  4,  Plate  XXVI,  figures  la-e. 

Holcctypns  planatns  Roemer,  1849,  Texas,  p.  393. 

Holrehipus  planaius  Roemer,  1852,  Die  Kreideliildungen  von  Texas,  p.  84,  PI.  X,  fig.  2. 

Holcctypns  planatus  Shuniard,  1852,  Exploration  Red  River  of  Louisiana  Rept.,  p.  211. 

Holectypus  planatus  Giebel,  1853,  Naturwiss.  Ver.  in  Halle  Jahresb.,  p.  373. 

Ilolectypus  planus  Giebel,  1853,  idem. 

Holcctypua  planatus  Conrad,  1857,  U.  S.  and  Mex.  Boundary  Survey  Rept..  vol.  1,  pt.  2,  p.  145,  PL  I,  fig.  4. 

Ilolectypus  planatus  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  174. 

Holectypus  planatus  Gabb,  18.59,  Cat.  Invert.  Fossils  Cretaceous,  p.  18. 

Holectypus  planatus 'Mee^^i,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 


66  MESOZOIC   AN^D   CENOZOIC    ECHINODEEMATA   OF    THE    UNITED    STATES. 

Holectypiis  sp.  Roemer.  1888,  Pal.  Abhandl.  von  Dames  und  Kayser,  vol.  4,  pt.  4,  p.  9  (287),  PI.  I  (XXXI),  figa.  6a-c. 

Eolcctijpus  planatus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 

Solectypiis  pla7mtus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  10.3,  p.  51. 

Holcctypus  planatus  Clark,  189.3,  U.  S.  Geol.  Survey  Bull.  97,  pp.  58,  59,  PI.  XXII,  figs.  2a-f. 

Eolecfypus  charltoni  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  158,  PI.  XXIV,  figs  8,  9. 

Holcctypus  planatus  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  pp.  159,  IGO. 

Holcctypus  trans pecosensis  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  160,  PI.  XXVII,  figs.  3-5. 

Holcctypus  charltoni  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  5,  p.  41. 

Holcctypus  planatus  Hill,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  7,  p.  226. 

Determinative  characters. — Test  subcircular,  subconical,  flattened  oa  the  under  surface. 
Ambulacra  narrow,  straight,  and  somewhat  lanceolate,  with  six  irregular  rows  of  tubercles; 
poriferous  zones  somewhat  straight,  narrow,  unigeminal.  Interambulacra  wide,  plates  mrnier- 
ous  .and  narrow,  each  ^vith  a  nearly  horizontal  row  of  small  tubercles,  .^.pical  system,  small,  the 
madreporite  large.     Peristome  small,  subcircular.     Periproct  large. 

Dimensions. — Transverse  diameter  12-70  millimeters;  lieight  7-40  millimeters. 

DescriiAion. — This  very  common  form  from  the  Cretaceous  of  Texas  was  first  reported  by 
Roemer  in  1849,  and  was  subsequently,  in  1852,  more  accurately  defined  and  figured  by  him. 
Although  wide  differences  in  outline  and  in  the  size  and  arrangements  of  the  tubercles  occur, 
they  appear  to  be  rather  individual  than  specific.  The  majority  of  the  specimens  are  subcir- 
cular; in  the  case  of  some,  however,  distinctly  circular,  while  in  that  of  others  clearly  pentagonal. 
The  ambitus  in  some  individuals  is  sharp,  in  others  rounded,  while  the  upper  surface  is  dis- 
tinctly elevated  at  the  center  with  slightly  tumid  sides.  The  under  surface  is  flat  and  slightly 
depressed  in  the  vicinity  of  the  peristome. 

The  ambulacra  are  narrow,  straight,  increasing  in  width  toward  the  ambitus  and  somewhat 
lanceolate  in  form.  The  poriferous  zones  are  narrow,  the  pores  small  and  unigeminal.  Six 
rows  of  small  tubercles  are  found  in  the  broader  portion  of  the  areas,  wliich  become  reduced  to 
four  toward  the  apical  disk  and  peristome. 

The  interambulacra  are  about  three  times  the  width  of  the  ambulacra  at  the  ambitus.  Tlie 
plates  are  narrow,  each  with  a  horizontal  row  of  small  tubercles,  five  or  six  in  a  row  at  the  am- 
bitus but  fewer  above  and  below.  Each  tubercle  has  a  smaU  circular  areola,  crenulated  boss, 
a,nd  perforated  mamelon.  The  tubercles  cover  the  greater  portion  of  the  plates,  with  minute 
granules  interspersed  between  them.  The  tubercles  are  very  much  larger  on  the  lower  surface, 
and  the  difference  in  size  shown  between  those  of  the  ambulacra  and  interambulacra  on  the 
upper  surface  disappears.  . 

The  apical  system  is  small.  The  five  ovarial  plates  are  all  perforated ;  the  madreporite  is 
of  large  size  and  indistinctly  separated  from  the  other  plates. 

The  peristome  is  smaU,  with  slight  incisions  that  give  a  decagonal  margin.  The  large  oval 
peristome  extends  from  the  vicinity  of  the  mouth  to  the  ambitus. 

Related  forms. — The  size  of  the  adult  forms  is  very  variable,  those  found  in  the  Wasliita 
group  being  larger  than  those  found  in  the  Trinity  and  Fredericksburg  group.  The  individuals 
also  vary  in  height.  So  many  connecting  forms  can  be  found  between  the  typical  H.  planatus 
and  the  species  described  as  H.  cJiarltoni  and  H.  trans  pecosensis  by  Cragin  that  they  have  been 
regarded  as  synonyms. 

Localities. — Near  Fredericksburg  (type),  Cow  Creek,  Travis  County  (figured  specimens  A 
and  B) ;  Denton  County  (figured  specimen  C) ;  Shoal  Creek,  Austin  (figured  specimen  D) ;  San 
Antonio,  Kent,  and  many  other  localities  in  Texas. 

Geologic  horizon. — Trinity,  Fredericksburg,  and  Washita  groups  of  the  Comanche  series, 
Cretaceous. 

Collections. ^JJ.  S.  National  Museum  (122.36);  Academy  of  Natural  Sciences  of  Phila- 
delphia; Boston  Society  of  Natural  History;  Geological  Survey  of  Texas;  Johns  Hopkins 
University  (T  3008). 


CEETACEOUS   ECHINODEKMATA.  67 

Suborder   CLYPEASTRINA. 
Family  CLYPEASTRID^. 

Genus  ECHINANTHUS  Leske. 

ECHINANTHUS  MORTONIS    (Micheliii). 

Pygorhynchus  mortonis  Miclielin,  1850,  Rev.  et  mag.  zoologie,  vol.  2,  p.  240. 
Hardouinia  mortoni  D'Archiac  and  Haime,  1853,  Foss.  numm.  de  I'lnde,  p.  214. 
Echinanthus  mortonis  Desor,  1858,  Synopsis  des  ^cliinides  fossils,  p.  295. 
Echinanthus  mortonis  Dujardin  and  Hup6,  1862,  Hist.  nat.  zoophytes  ecliin.,  p.  584. 
EcMnanthus  mortonis  Coiu-ad,  18C5,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  75. 
Echinanthus  mortonis  Conrad,  1866,  Check  list,  p.  22. 
Echinanthus  mortonis  Quenstedt,  1872-1875,  Petrefac.  Deutsch.,  p.  692. 

Description. — The  author  has  been  unable  to  examine  a  specimen  of  this  species.  Desor 
gives  the  following  description: 

Espfece  remarquable  entre  tons  les  Echinanthus  par  sa  forme  elevee,  conique,  a  peu  prfes  aussi  large  que  longue, 
rappelant  un  peu  les  Pygurus  par  sa  physionomie.  Sommet  ambulacraire  l^gferement  excentrique.  Petales  larges, 
pointus  a  leur  extremity,  depassant  un  peu  la  moitie  de  la  distance  entre  le  sommet  et  le  bord.  P^riprocte  grand, 
situ6  h  mi-distance  du  sommet,  a  I'origine  d'un  large  et  profond  sillon.  Dessous  concave.  Peristome  a  peu  prfes 
central,  petit,  entour6  d'un  floscelle  trfes  accuse. 

D'Archiac  and  Haime  proposed  to  make  of  this  species  the  type  of  a  new  genus  which  they 
called  Hardouinia.  Notwithstanding  the  fact  that  the  floscelle  is  somewhat  more  pronounced 
than  in  any  of  the  other  species  Desor  and  others  who  examined  the  form  considered  that  the 
characters  were  not  sufficiently  pronounced  to  justify  a  generic  separation  from  Echinanthus. 

Locality. — Pontotoc,  Miss. 

Geologic  horizon. — Ripley  formation,  Upper  Cretaceous.  The  reference  of  this  form  to  the 
Tertiary  by  earlier  authors  is  evidently  incorrect. 

Collection. — Unknown.     Desor  mentions  its  presence  in  the  collection  of  Verneuil. 

Genus  SCUTE LL ASTER  (?)  Cragin. 
? ScuTELLASTER  CRETACEus  Cragin. 
Scutellaster  cretaceus  Cragin,  1895,  Am.  Geologist,  vol.  15,  pp.  90,  91. 

Description. — The  specimen  on  which  this  genus  and  species  are  based  is  so  imperfect  that 
it  seems  better  to  defer  the  acceptance  of  both  until  more  diagnostic  material  is  obtained. 
Cragin  in  a  letter  to  the  author  says:  "I  fear  it  [Scutellaster]  is  not'  after  all  a  new  genus  as 
I  supposed  when  I  described  it  as  such." 

Locality. — East  slope  of  Shooks  Run,  Piatt  Avenue,  Colorado  Springs,  Colo. 

Geologic  horizon. — ^Arenaceous  shale  of  Fox  Hills  sandstone  of  Montana  group,  Upper 
Cretaceous. 

Collection. — Colorado  College. 

Order  ATELOSTOMATA. 

Suborder  ASTERNATA. 

Family  ECHINONEID.E. 

Genus  PYRINA  Desnioulins  emend.  De  Loriol. 
Pyrina  parryi  Hall. 

Plate  XXVII,  figures  la-j. 

Pyrina  parryi  Hall,  1857,  U.  S.  and  Mex.  Boundary  Survey  Rept.,  vol.  1,  pt.  2,  p.  144,  PI.  I,  figs.  1-ld. 
Pyrina  parryi  Gahh,  1859,  Catalogue  Invertebrate  Fossils  Cretaceous,  p.  19. 
Pyrina  parryi  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 
Pyrina  parryi  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 


68  MESOZOIC   AND   CENOZOIC    ECHIXODEEMATA    OF    THE    UJTITED    STATES. 

Pyrina  parryi  Aguilera,  1893,  Datos  para  la  geologfa  de  Mexico,  p.  26. 
Pyrina  parryi  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Pyrina  parryi  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  59,  60. 
Pyrina  bulloides  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  162. 
Pyrina  parryi  Aguilera,  1897,  Inst.  geol.  Mexico  Bol.  Nos.  4,  5,  6,  p.  215. 
Pyrina  parryi  Bos^,  1899,  Inst.  geol.  Mexico  Bol.  No.  13,  p.  11. 

Determinative  characters. — Test  subpent agonal,  broader  anteriorly  than  posterioriy,  inflated 
at  the  sides,  flattened  above  and  below.  Ambulacra  narrow,  imiserial ;  both  areas  covered  with 
minute  tubercles. 

Peristome  large,  elliptical,  oblique.     Periproct  oval,  supramarginal. 

Dimensions. — Length  20  to  35  millimeters;  width  18  to  30  millimeters;  height  12  to  25 
millimeters. 

Description. — The  test  is  regular  and  symmetrical,  slightly  pentagonal  in  outline,  enlarged 
anteriorally,  contracted  posteriorly.  •  The  upper  surface  is  convex,  although  somewhat  flatteiaed 
at  the  summit.  The  sides  are  inflated,  the  base  flattened  and  slightly  depressed  in  the  vicinity 
of  the  peristome. 

Tlie  ambulacra  are  narrow  and  lanceolate;  the  poriferous  zones  straight  and  depressed, 
the  pores  small,  oval,  and  uniserial.  The  interambulacra  are  broad  and  less  elevated  than  the 
ambulacra.  Both  the  ambulacra  and  the  interambulacra  support  numerous  small  tubercles 
that  are  larger  and  more  distinct  on  the  lower  than  the  upper  surface.  Fine  microscopic  gran- 
ules are  disseminated  between  the  tubercles. 

The  peristome  is  large,  elliptical,  and  obliquely  situated  slightly  in  front  of  the  center  of  the 
base.  The  periproct  is  oval  and  placed  nearly  in  the  center  of  the  posterior  margin.  The  apical 
system  is  small,  composed  of  four  genital  plates,  the  large  right  antero-lateral  modified  to  form 
the  madreporite.     The  five  small  ocular  plates  are  firmly  wedged  between  the  ovarial  plates. 

Related  forms. — The  species  just  described  is  the  only  representative  of  this  genus  from 
American  strata  and  both  in  form  and  structm-al  features  admits  of  a  ready  separation  from  all 
European  species.  It  presents  some  points  of  similarity  with  Pyrina  desmoulinsii  D'Archiac, 
but  is  broader  posteriorly  and  less  elevated.  The  many  specimens  of  this  common  species  which 
have  come  under  the  observation  of  the  author  show  considerable  variation,  but  are  all  regarded 
as  representing  a  single  species. 

Localities. — Leon  Springs  (type),  near  San  Antonio,  Pilot  Knob  (Travis  County),  Kent, 
Sierra  Blanca  peaks,  and  many  other  localities  in  Texas. 

Geologic  horizon. — Fredericksburg  and  Washita  groups,  Comanche  series,  Cretaceous. 

Collections. — U.  S.  National  Museum  (9854) ;  Johns  Hopkins  University. 

Family  NUCLEOLITID.E. 

Genus  BOTBIOPyGUS  D'Orbigny. 

BOTRIOPYGUS    ALABAMENSIS    Clark. 

Plate  XXIV,  figures  2a-f. 

Botriopygus  alahamcnsis  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Botriopygus  alabamensis  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  51. 
Botriopygus  alabamensis  Clark,  1893,  U.  S.  Geol.  Sm-vey  Bull.  97,  pp.  60,  61,  PI.  XXV,  figs.  la-f. 

Determinative  characters.— Test  oblong;  more  or  less  depressed  on  upper  surface,  highest 
anteriorly;  under  surface  concave.  Ambulacra  broad,  lanceolate;  poriferous  zones  subpetaloi- 
lal  above.  Interambulacral  plates  covered  Math  numerous,  irregularly  distributed  tubercles, 
i.nical  system  anteriorly  situated.     Peristome  small,  oblique,  forward  of  the  center. 

Dimensions.— L,engih  63  millimeters;  width  54  millimeters;  height  26  millimeters. 

Description. — The  single  imperfectly  preserved  specimen  of  this  species,  although  apparently 
lacking  some  of  the  characteristics  of  Botriopygus,  is  nevertheless  referred  to  that  genus.  The 
test  is  oblong,  considerably  depressed  on  the  upper  surface,  and  concave  on  the  base.     The  apex 


CRETACEOUS  ECHINODEKMATA.  69 

of  the  Upper  surface  is  forward  of  tlie  center,  making  the  anterior  margin  full,  the  posterior 
flattened. 

The  ambuLacra  are  broad  and  lanceolate.  They  contract  appreciably  just  above  the  ambi- 
tus, giving  to  the  poriferous  zones  a  subpetaloidal  form.  The  pores  of  the  subpetaloidal  portions 
are  large  and  oval,  those  of  the  outer  rows  more  elongated  than  those  of  the  inner  ancl  acumi- 
nated on  their  inner  margins.  The  pores  of  each  pair  are  united  by  a  furrow.  The  inner  por- 
tions of  the  ambulacra]  plates  are  covered  with  tubercles,  which  in  the  broadest  portion  of  the 
subpetaloidal  areas  reach  five  or  six  in  number.  Below  the  subpetaloidal  areas  the  pores  recede 
from  the  outer  margin  of  the  plates.  Those  of  each  pair  are  close  together,  small,  and  nearly 
round,  and  the  plates  also  become  broader. 

The  interambulacral  plates  are  large  and  covered  with  numerous,  irregularly  arranged  tuber- 
cles.    A  microscopic  granulation  covers  the  intertubercular  space. 

The  position  of  the  apical  system  is  forward  of  the  center  of  the  upper  surface,  although  none 
of  the  plates  are  preserved  on  the  specimen  examined.  The  peristome  is  small  and  oblicpiely 
placed  slightly  in  front  of  the  center  of  the  base. 

Belated  forms. — Under  the  name  of  B.  elevatus  Gabb  describes  a  species  from  Peru  that  is  not 
unlike  B.  alabamensis  in  many  particulars.  B.  alabamensis,  however,  is  larger,  less  rounded  ante- 
riorly, and  has  a  more  depressed  posterior  margin. 

Locality. — Alabama. 

Geologic  Tiorizon. — Ripley  formation,  Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia. 

Genus  ECHINOBRISSUS  Breyn. 

EcHiNOBRissus  ANGUSTATUs  Clark,  n.  sp. 

Plate  XXVII,  figures  2a-c. 

Determinative  character s.— Test  small,  subovate,  rounded  anteriorly,  subquadrate  poste- 
riorly; upper  surface  elevated;  apex  forward  of  the  center;  base  concave.  Ambulacra  lanceo- 
late. Peristome  small,  excentric ;  periproct  small  in  broad  shallow  sulcus,  placed  well  posteri- 
orly. 

Dimensions. —  Length  15.5  millimeters;  width  14  millimeters;  height  8.5  millimeters. 

Description.— This  small  form  is  subovate  in  ambital  outline,  is  rounded  anteriorly  and 
truncated  posteriorly,  giving  a  subquadrate  effect.  The  upper  surface  is  elevated  and  the  lower 
concave. 

The  ambulacra  are  very  indistinct  on  the  type.  The  apical  system  is  forward  of  the  center 
but  the  individual  plates  are  indistinguishable.  The  peristome  is  small,  deeply  depressed  and 
excentric  in  front.     The  periproct  is  small  in  a  broad  shallow  sulcus  and  placed  well  posteriorly. 

Locality. — Shoal  Creek,  Tex. 

Geologic  Tiorizon. — Buda  (Shoal  Creek)  limestone  of  Washita  group,  Comanche  series,  Cre- 
taceous. 

Collection. — Johns  Hopkins  University  (T  3009). 

ECHINOBRISSUS   EXPANSUS   Clai'k. 

Plate  XXVIII,  figures  la-g. 

Echinobrissus  expansus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.10,  No.  87,  p.  76. 
Echinobrissiis  expansus  Clark,  1893.  Johns  Hopkins  Univ.  Circ,  vol  12,  No.  103,  p.  52. 
Echinobrissus  rxpansiis  Clark,  ISnS,  U.  S.  Geol.  Survey  Bull.  97,  pp.  61,  62,  PI.  XXVI,  figs.  la-g. 
Echinobrissus  fx.pansiis  Johnson,  190.5,  Acad.  Nat.  Sci.  Philadelphia  Proc.  vol.  57,  p.  6. 

Determinative  characters. — Test  subquadrate,  broader  posteriorly,  moderately  convex  on 
upper  surface,  concave  on  the  base.  Ambulacra  narrowly  lanceolate.  Periproct  large,  supra- 
marginal;  anal  sulcus  broad,  deep,  extending  from  near  the  apex  to  the  ambitus.  Peristome 
large,  situated  in  front  of  the  middle  of  the  base. 


70  MESOZOIC    AND   CEXOZOIC   ECHINODERMATA   OF    THE    UNITED    STATES. 

Dimensions. — Lengtli  27  millimeters;  width  27  millimeters;  height  12  millimeters. 

Description. — This  typical  Echinobrissus  is  of  a  moderate  size,  somewhat  depressed  above, 
and  subquadrate  in  marginal  outline.  The  posterior  portion  is  broader  than  the  anterior  and 
distinctly  lobed.     The  base  is  concave. 

The  ambulacral  areas  are  narrowly  lanceolate,  and  on  the  upper  surface  tlie  poriferous  zones 
are  subpetaloidal.  The  inner  rows  of  pores  are  round,  the  outer  oval,  with  acuminated  inner 
margins  and  obliquely  placed.  The  interambulacral  areas  are  formed  of  broad  plates  that  bear 
numerous  small  peiforated  and  mammillated  tubercles.  A  microscopic  granulation  covei-s  the 
miliary  space. 

The  apical  system  is  small  and  compact  and  the  perforations  of  the  genital  plates  distinct. 

The  peristome  is  large,  excentric,  situated  at  some  distance  in  front  of  the  center  of  the  base. 
The  periproct  is  large,  acuminated  on  the  upper  margin,  and  placed  in  a  broad,  deep  anal  sulcus 
that  extends  from  near  the  apical  system  to  the  posterior  margin. 

Related  forms. — Ediinohrissus  expansus  has  few  points  that  would  closely  ally  it  with  any 
species  of  this  genus  hitherto  described. 

Locality. — Alabama   or   Mississippi. 

Geologic  horizon. — Ripley  formation.  Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1465). 

Echinobrissus  texanus  Clark. 

Plate  XXVIII,  figures  2a-f. 

Echinobrissus  t£xa/ius  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol  10,  No.  87,  p.  76. 
Echinobrissus  texanus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Echinobrissus  texanus  Clark,  1893,  U.  S.  Geol.  Sur\'ey  Bull.  97,  pp.  62,  63,  PI.  XXVI,  figs.  2a-f. 
Echinohrissvs  teaxams  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  150. 

Determinative  characters. — Test  ovate,  rounded  anteriorly,  subquadrate  posteriorly;  upper 
surface  convex,  apex  foi-ward  of  the  center;  base  concave.  Ambulacra  lanceolate,  subpetaloidal. 
Apical  system  forward  of  the  center.  Peristome  small,  excentric.  Periproct  small,  oval,  in 
narrow  sulcus  that  begins  some  distance  below  the  apical  disk. 

Dimensions. — Length  18.75   millimeters;  \vidth  16.5  millimeters;  height   9.5  millimeters. 

Description. — The  single  specimen  of  this  species  is  somewhat  damaged  on  the  sides,  so  that 
the  ambital  outline  is  not  complete.  It  is  ovate  in  form,  broader  posteriorly  and  subquadrate. 
The  upper  surface  is  convex,  but  more  or  less  compressed.     The  lower  surface  is  concave. 

The  ambulacra  are  narrowly  lanceolate.  The  poriferous  zones  for  a  short  distance  from  the 
apical  system  are  subpetaloidal  in  form.  The  posterior  ambulacra  are  much  longer  than  the 
others,  the  impaired  ambulacrum  being  the  shortest.  The  pores  of  each  plate  are  oval  and  set 
at  an  angle  to  one  another. 

The  interambulacral  plates  are  large  and  covered  vnih  irreguarly  arranged  tubercles. 
Between  the  tubercles  a  microscopic  granulation  covers  the  siuiace. 

The  apical  system  is  small  and  situated  forward  of  the  apex.  The  individual  plates  can  not 
be  fully  distinguished  on  the  specimen  examined.  The  peristome  is  apparently  small,  though 
somewhat  obscured.     It  is  situated  forward  of  the  center  of  the  base. 

The  periproct  is  small,  placed  in  a  narrow  sulcus  that  begins  some  distance  posterior  to  the 
apical  system. 

Related  forms. — Echinobrissus  texanus  is  readity  separated  from  E.  expansus  bj^  its  ovate 
form  and  the  shape  and  size  of  the  anal  sulcus.     It  is  milike  any  Em-opean  species. 

Locality. — South  bank  of  Colorado  River,  Austin,  Tex. 

Geologic  horizon. — Austin  chalk,  Upper  Cretaceous. 

Collection. —U .  S.  National  Museum  (20266). 


CRETACEOUS   ECHINODEEMATA.  71 

Genus  TREMATOPYGUS  D'Orbigny. 
Trematopygus  crucifeeus  (Morton). 
Plate  XXVIII,  figures  3a-c;  Plate  XXIX,  figures  la-f. 

Ananchytes  cniciferus  Morton,  1830,  Am.  Jour.  Sci.,  Istser.,  vol.  IS,  p.  24.5,  PI.  Ill,  fig.  8. 

Ananchijlcs  cruciferus  Morton,  1830,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  Istser.,  vol.  6,  pp.  201,  202. 

NudeoUles  crucifcr  Morton,  1833,  Am.  Jour.  Sci.,  Istser.,  vol.  23,  p.  294. 

NudeoJites  crucifcr  Morton,  1834,  Synopsis  .Organic  Remains  Cretaceous,  p.  75,  PI.  Ill,  fig.  1-5.  • 

NudeoUtes  crucifcrus  Agassiz,  1840,  Catalogus  systematicus,  p.  4. 

Nuculites  crucifcrus  Agassiz  and  Dosor,  1847,  Catalogue  raisonne,  p.  97. 

Nuculites  crucifcr  Bronn,  1848,  Index  paliseontologicus,  vol.  1,  p.  818. 

NudeoUles  crucifcrus  D'Orbigny,  18.50,  Prodrome,  vol.  2,  p.  271,  6tage  22,  No.  1197. 

Pygorhynchus  crucifcr  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  p.  160. 

Trematopygus  crucifcr  D  'Orbigny,  18.53-60,  Pali^ontologie  franfaise,  vol.  6,  p.  387,  PI.  CMLIII,  figs.  10, 11;  PI.  CMLXIII, 

figs.  1-5. 
Echinohrissus  crucifcr  D'Orhigny,  1854,  Rev.  et  mag.  zoologie,  ser.  2,  vol.  6,  p.  25. 
NudeoUtes  crucifcr  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  262. 
NucuUtes  crucifcr  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 
NucuUtes  crucifcr  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 
NucuUtes  crucifcr  Cook,  1808,  Geology  of  New  Jersey,  p.  377. 
NucuUtes  crucifcr  Conrad,  1868,  Geology  of  New  Jersey,  App.  A,  p.  722. 
NucuUtes  crucifcrus  Credner,  1870,  Deutsche  geol.  Gesell.  Zeitschr.,  vol.  22,  p.  217. 
Trematopygus  crucifer  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Trematopygus  crucifer  Clark,  1893,  Jolin.i  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Trematopygus  crucifcr  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  63,  64,  PI.  XXVII,  figs.  la-i. 
Trematopygus  crucifer  Johnson ,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 
Trematopygus  crucifcrus  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  289-290, 

PI.  XI,  figs.  1-9. 

Determinative  characters. — Test  ovate,  inflated  at  the  sides  and  base  and  slightly  con- 
tracted anteriorly.  Ambulacra  long,  well  defined;  pores  uniserial,  prominent  on  the  upper  sur- 
face, indistinct  on  tlie  base.  Apical  system  situated  anteriorly.  Peristome  large  and  oblique. 
Periproct  large,  oval,  supramarginal. 

Dimensions. — Length  18  to  20  millimeters;  breadth  15  to  22  millimeters;  height  10  to  14 
millimeters. 

Description. — ^This  species  is  not  uncommon  at  Timber  Creek,  N.  J.,  where  many  very  perfect 
specimens  have  been  obtained.  Its  outline  is  ovate  and  very  regular,  lacking  at  the  ambitus  or 
apex  any  sharply  defined  angularity.  The  sides  are  highly  inflated  together  with  the  outer 
portion  of  the  base. 

Tlie  ambulacra  are  long,  lanceolate,  and  unequal;  the  posterior  pair  are  the  longest,  the 
mipaired  anterior  one  is  the  shortest.  They  do  not  produce  any  irregularity  in  the  outline  of 
the  test  beyond  inconsiderable  depressions  in  the  immediate  vicinity  of  the  peristome.  The 
poriferous  zones  are  clearly  marked  on  the  upper  surface,  and  the  pore  pairs  are  nearly  horizontal, 
but  toward  the  ambitus  the  pores  become  smaller,  those  of  each  jjair  nearer  together,  and  the 
pairs  obliquely  situated  at  the  lower,  outer  corner  of  each  plate;  near  the  peristome  they  again 
become  larger  and  slightly  increased  in  number. 

The  interambulacra  are  wide  and  composed  of  large  plates  that  are  bent  in  the  middle. 
The  surface  is  covered  with  irregular  rows  of  tubercles  that  are  perforated  and  mammillated. 
The  miliary  space  is  covered  with  numerous  minute  and  irregularly  distributed  granules. 

The  apical  system  is  small  and  anteriorly  situated;  the  toui'  genital  plates  are  distinctly 
perforated ;  those  of  the  anterior  pair  are  much  nearer  together  than  those  of  the  jJosterior. 

The  peristome  is  large,  oblique,  and  placed  somewhat  forward  of  the  center  of  the  base. 
The  periproct  is  large,  oval,  and  acuminate  at  the  upper  extremity.  It  is  situated  in  an  anal 
sulcus  that  makes  a  marked  indentation  in  the  posterior  margin,  and  is  bordered  by  two  well- 
detmed  ridges. 

Related  forms. —  Trematopygus  cruciferus  (Morton)  is  a  unique  species  that  has  no  closely 
allied  forms  in  either  American  or  European  deposits. 


72  MESOZOIC    AND   CENOZOIC    ECHINODEKMATA    OF    THE '  UNITED    STATES. 

Locality. — The  yellow  limestone  of  Timber  Creek  and  Vincentown  (type),  N.  J. 
Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 
Collections. — American  Museum   of  Natural   History,  New  York;   Academy  of  Natural 
Sciences  of  Philadelphia  (1464);  Johns  Hopkins  University. 

Family  CASSIDULID^. 

Genus  PYGTJBUS  Agassiz. 

?Pygukus  geometricus  (Morton). 

Clypeaster  sp.  Morton,  1830,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.,  vol.  6,  p.  202. 

Clijpraskr  geometricus  Morton,  1833,  Am.  Jour.  Sci.,  1st  ser.,  vol.  24,  p.  131,  PI.  X. 

Clypeaster  geometricus  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  7fi,  PI.  X,  fig.  10. 

Pygurus  geometricus  Agassiz  and  Desor,  1847,  Catalogue  raisonn^,  p.  141. 

Clypeaster  geometricus  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  312. 

Pygurus  geometricus  D'Orbigny,  1850,  Prodrome,  vol.  2,  p.  270. 

Pygurus  geometricus  D'Orbigny,  1853-60,  Paleontologie  fran^aise,  vol.  6,  p.  313,  PI.  CMXX,  fig.  4. 

Pygurus  geometricus  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  313. 

Clypeaster  geometricus  Gabb,  1859,  Catalogue  Invertebrate  Fossils  Cretaceous,  p.  18. 

Pygurus  (?)  geometricus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Pygurus  (?)  geometricus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  92,  93. 

Pygurus  (?)  geometricus  Johnson,  1905,  Acad.  Nat.  Sci.  Pliiladelphia  Proc,  vol.  57,  p.  7. 

The  type  of  this  species  was  examined  b}^  the  writer,  but  its  state  of  preservation  (that  of  a 
poor  cast)  is  such  that  its  generic  relations  can  not  be  with  certainty  determined.  Until  further 
material  is  obtained  it  seems  best  to  defer  its  recognition.  Although  originally  described  by 
Morton  as  a  Clypeaster,  it  has  been  referred  to  the  genus  Pygurus  by  Agassiz,  D'Orbigny,  and 
Desor. 

Locality. — Delaware  and  Chesapeake  Canal,  Delaware. 

Geologic  horizon. — Matawan  formation,  Upper  Cretaceous. 

Collection. — ^Academy  of  Natural  Sciences  of  Philadelphia. 

Genus  CATOPYGUS  Agassiz. 

Catopygus  oviformis  Conrad. 

Plate  XXIX,  figures  2a-l". 

Catopygus  oviformis  Conrad,  1847,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  2,  p.  39,  PL  I,  fig.  9. 
Nuelcolites  oviformis  (Catopj'gus)  Conrad,  1868,  Geology  of  New  Jersey,  App.  k,  p.  722. 
Catopygus  oviformis  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  70. 
Catopygus  oviformis  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Catopygus  oviformis  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  64,  65,  PI.  XXVII,  figs.  2a-f. 
Catopygus  oviformis  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Determinative  characters. — Test  ovate,  broader  posteriorly;  upper  surface  nearly  flat;  apex 
posterior  to  apical  disk.  Ainbulacra  narrow,  subpetaloidal.  Interambulacra  wide;  single  inter- 
ambulacrum  elevated.  Apical  system  excentric,  nearer  the  anterior  border.  Peristome  small, 
excentric,  nearer  the  anterior  margin.  Periproct  oval,  situated  in  a  narrow  sulcus,-  that  termi- 
nates above  in  a  projecting  arch. 

Dimensions. — Characteristic  specimen:  Length  25  millimeters;  width  21.9  millinaeters ; 
height  14  millimeters. 

Description. — The  test  of  this  very  beautiful  little  form  is  ovate,  with  rounded,  inflated 
sides  and  elevated  upper  surface.  The  base  is  nearly  flat,  slightly  concave  in  the  vicinity  of  the 
peristome,  and  lobed  posteriorly. 

The  ambulacra  arc  narrowly  lanceolate,  subpetaloidal  on  the  upper  surface,  the  posterior 
areas  being  much  longer  than  the  others.  The  plates  in  the  petaloid  portions  are  narrow  but 
beyond  increase  in  breadtli. 

The  interambulacral  plates  are  covered  with  minute  tubercles,  between  which  are  numerous 
microscopic  granules. 


CEETACEOUS    ECHIKODERMATA.  73 

The  apical  sy.^tem  is  small,  excentric,  and  situated  far  anterior  to  the  apex. 

The  peristome  is  small  and  situated  nearer  the  anterior  margui. 

The  periproct  is  oval  and  placed  at  the  upper  part  of  a  nearly  vertical  anal  sulcus.  The 
upper  margm  of  this  sulcus  forms  a  beak-shaped  prominence  that  overhangs  the  opening. 

Related  forms. — C.  ovifonnis  is  separated  from  C.  pusiUus  Clark,  by  its  narrower  outline, 
more  inflated  sides,  and  the  anterior  position  of  its  apical  system.  In  form  it  is  somewhat  like 
C.  colujnharius  of  Europe,  but  is  distinguished  from  it  by  the  position  of  the  apical  system. 

Locality. — Timber  Creek,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group.  Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1477). 

Catopygus  pusillus  Clark. 
Plate  XXIX,  figures  3a-d. 

■Catopygus  pusillus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Catopygus  pwsillus  Clark,  189.3,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Catopygus  pusillus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  65,  66,  PI.  XXVll,  figs.  3a-d. 

Catopygus  pusillus  W'eWer,  1907,  Cretaceous  paleontology  of  New  Jersey:  Cieol.  Survey  New  Jersey,  p.  292,  Pi.  XI, 
figs.  16-19. 

Determinative  cliaracters. — Test  ovate  to  subquadrate,  rounded  anteriorly,  subquadrate 
posteriorly,  broader  behind  than  before;  upper  surface  elevated;  base  concave.  Ambulacra 
narrowly  lanceolate,  subpetaloidal  on  the  upper  surface.  Apical  system  small,  nearly  central. 
Peristome  small,  anteriorly  placed.     Periproct  oval  in  vertical  sulcus  beneath  overhanging  arch. 

Dimensions. — Characteristic  form:  Length  15.6  millimetei-s ;  width  14  millimeters;  height 
9.4  millimeters. 

Description. — All  the  specimens  of  this  species  examined  by  the  writer  are  casts,  which  are, 
however,  sufficiently  well  preserved  to  allow  determination  of  aU  the  more  important  characters. 
The  test  is  ovate  to  subquadrate,  occasioned  by  the  slight  angularity  of  the  posterior  margin. 
The  anterior  portion  is  regularly  rounded. 

The  ambulacra  are  narrow,  the  posterior  pair  only  slightly  longer  than  the  anterior. 

The  interambulacra  are  wide  and  composed  of  large  plates. 

The  apical  system  is  small  and  situated  nearly  in  the  center  of  the  upper  surface. 

The  peristome  is  small  and  placed  forward  of  the  center  of  the  base.  The  periproct  is  situ- 
ated in  a  nearly  vertical  sulcus  that  is  overhung  at  its  upper  extremity  by  a  projecting  arch. 

Related  forms. — Catopygus  pusillus  is  separated  from  C.  oviformis  by  its  broader  and  slightly 
subquadrate  form,  its  less  rounded  sides,  and  nearly  central  position  of  its  apical  system. 

Locality. — ^Wordills,  Monmouth  County,  X.  J. 

Geologic  horizon. — ^Merchantville  clay  of  Matawan  group,  Upper  Cretaceous. 

Collection. — -U.  S.  National  Museum  (2210). 

Catopygus    williamsi   Clark. 
Plate  XXIX,  figures  4a-d. 

Catopygus  wilHarrm  Clark,  1907;  in  Weller,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersej-,  pp. 
292-293,  PI.  XII,  figs.  1-4. 

Determinative  characters. — Test  ovate,  slightly  broader  posteriorly;  upper  surface  rounded 
and  somewhat  elevated;  lower  surface  concave.  Apex  posterior  to  apical  system.  Ambidacra 
subpetaloidal.  Peristome  small,  near  anterior  margin.  Periproct  small,  low  down  on  slightly 
truncated  posterior  margin. 

Dimensions. — Length  26  mdlimeters;  width  22  millimeters;  height  1.5  millimeters. 

Description. — The  single  specimen  of  this  si:)ecies  is  a  well-preserved  cast  that  clearly  shows 
all  of  the  more  important  diagnostic  features.  The  test  is  ovate,  slightly  broader  posteriorly. 
The  posterior  margin  is  but  little  truncated,  affording  a  nearly  oval  outline  to  the  ambitus. 
The  upper  siu-f ace  is  somewhat  elevated,  but  it  is  not  a  highly  inflated  form.  The  lower  surface 
is  clearly  concave. 


74  MESOZOIC   AND   CENOZOIC    ECHINODEKMATA   OF    THE    UNITED    STATES. 

The  ambulacra  are  subpetaloidal  on  the  upper  surface.  The  posterolateral  ambulacra 
are  somewhat  longer  than  the  others. 

The  apical  system  is  slightlj'  excentric,  being  situated  anterior  to  the  apex. 

The  peristome  is  small,  pentapetaloidal  and  situated  well  anteriorly.  The  periproct  is 
small,  low  down  on  the  overhanging,  truncated  posterior  margin. 

Related  forms. — This  species  is  distinct  from  either  C.  ovifonnis  or  C.  pusillus.  Its  posterior 
margin  and  the  position  of  its  periproct  very  readily  separate  it. 

Locality. — ^Bluff  east  of  Atlantic  Higlilands,  N.  J. 

Geologic  horizon. — Navesink  marl  of  Monmouth  group,  Upper  Cretaceous. 

Collection. — Johns  Hopkins  University  (T  3010). 

Catopygus  sp. 
Catopygus  sp.  indet.  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  p.  293. 

A  poorly  preserved  specimen  of  Catopygus  presents  some  points  of  similarity  to  C.  pusiUus 
but  apparently  differs  from  it  in  other  featm-es.  In  its  imperfect  state  of  preservation  it  can 
not  be  assigned  with  certainty  to  that  species.  Some  of  the  most  important  diagnostic  charac- 
ters are  lacking. 

Locality. — Beers  Hill  Cut,  south  of  Keyport,  N.  J. 

Geologic  horizon. — Tinton  sand  member  of  the  Redbank  sand,  Monmouth  group,  Upper 
Cretaceous. 

Collection. — New  Jersey  Geological  Survey. 

Genus  CASSIDTJLTTS  Lamarck. 

Cassidxjlxis  florealis  (Morton). 

Plate  XXX,  figures  la-1. 

Clypeaster  sp.  Morton,  1830,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.   vol.  6,  p.  202. 

Cly peastcr  florenlis  '^iorton,  1S33,  Am.  Jour.  Sci.,  1st  ser.,  vol.  23,  p.  294. 

Clypeaster  florealis  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  76,  PI.  Ill,  fig.  12,  and  PI.  X,  fig.  12. 

Pygurus  florealis  Agassiz  and  Desor,  1847,  Catalogue  raisonn^,  p.  141. 

Clypeaster  florealis  Bronn,  1848,  Index  palaeontologicus,  p.  312. 

Faujasia  florealis  D'Orbigny,  18.53-1860,  Pal^ontologie  franfaise,  vol.  6,  p.  319,  PI.  CMXX,  figs.  5,  6. 

Faujasia  florealis  Desor,  1858,  Synopsis  des  ecliinides  fossiles,  p.  318. 

Clypeaster  florealis  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  18. 

Cassidulus  florealis  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 

Pygurus  florealis  Conrad,  1868,  Geology  of  New  Jersey,  App.  A,  p.  722. 

Cassidulus  florealis  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 

Cassidulus  florealis  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Cassidulus  florealis  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  66,  67,  PI.  XXVIII,  figs.  la-1. 

Cassidulus  florealis  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Determinative  characters. — Test  subcorneal  in  outline,  subpentagonal,  slightly  longer  in 
the  anteroposterior  diameter  than  the  lateral,  rounded  anteriorly,  angular  posteriorly;  apex 
slightly  forward  of  the  center.  Ambulacra  narrow;  poriferous  zones  petaloidal  on  the  upper 
two-thirds  of  the  dorsal  sm-face.  Interambulacra  wide,  covered  with  small  perforated  tubercles. 
Apical  system  small,  situated  anteriorly.  Peristome  pentagonal,  with  weU  developed  floscelle. 
Periproct  supramarginal,  in  a  short,  narrow  sulcus. 

Dimensions. — Length  3.5  millimeters;  breadth  32  millimeters;  height  19  millimeters. 

Description. — This  species,  the  earliest  of  this  genus  recognized  from  American  deposits, 
has  a  subconical  test  of  moderate  height,  with  a  subpentagonal  margin.  The  angxilarity  is  more 
pronounced  posteriorly  than  anteriorly,  the  anterior  portion  of  the  margin  being  distinctly 
rounded.  The  anteroposterior  diameter  is  but  shghtly  greater  than  the  lateral,  while  the  height 
is  a  little  more  than  one-half  of  the  same.  The  apex  is  a  short  distance  in  front  of  the  center 
of  the  upper  surface,  the  slope  of  the  anterior  face  being  sharper  than  that  of  the  posterior. 

The  ambulacra  are  narrow.  The  poriferous  zones  consist  of  a  double  row  of  pores  that  are 
arranged  in  petaloidal  form  on  the  upper  two-thirds  of  the  dorsal  surface  and  as  phylloidal 
expansions  in  the  vicinity  of  the  mouth  edges.     In  the  petaloidal  portion  the  pores  of  the  inner 


CEETACEOUS   ECHINODEKMATA.  75 

row  are  oval,  those  of  the  outer  elongated,  and  each  pair  united  by  a  shallow  furrow.  Toward 
the  margin  the  pores  are  smaller  and  placed  near  together  and  so  continue  until  near  the  peris- 
tome, where  the  poriferous  zones  suddenly  expand.  At  this  point  the  pores  increase  in  size  and 
distance  from  one  another.  Between  the  oral  lobes  the  poriferous  zones  again  suddenly 
contract. 

The  interambidacra  are  of  luiequal  width;  the  anterior  pair  are  the  narrowest;  the  three 
posterior  are  of  about  equal  width  and  nearly  one-half  wider  than  the  anterior.  The  surface  of 
the  plates  is  irregularly  covered  with  numerous  small  perforated  tubercles,  with  sunken  areolas 
between  which  are  numerous  microscopic  granules. 

The  apical  system  is  composed  of  four  perforated  genital  and  five  small  ocular  plates.  The 
fifth  genital  is  obsolete.  The  large  right  anterolateral  genital  plate,  the  madreporite,  extends 
across  the  disk,  forming  a  large  portion  of  the  center  of  that  body. 

The  peristome  is  large,  pentagonal,  and  shghtly  nearer  the  anterior  margin.  It  is  sur- 
rounded by  five  prominent  lobes  that  project  over  the  oral  opening.  The  ambulacra  are  con- 
tracted between  the  lobes  and  expand- beyond  them  into  wide  phylloidal  areas,  producing  a 
peculiar,  somewhat  star  shaped  form  that  has  been  termed  the  floscelle. 

The  periproct  is  small,  circidar,  and  supramarginal,  and  is  situated  in  a  short,  narrow  sulcus. 

Related  forms. — Cassidulus  Jlorealis  is  allied  to  C.  sequoreus,  although  the  latter  is  more 
depressed  and  more  elongated.  In  some  points  it  is  similar  to  C.  subconicus  but  has  a  less 
sharply  defined  pentagonal  outline,  a  differently  situated  periproct,  and  less  elongated  pores 
in  the  outer  rows  of  the  petaloidal  areas. 

Localities. — Chesapeake  &  Delaware  Canal,  Del.  (tj'pe) ;  Uniontown,  Ala. 

Geologic  horizon. — Matawan  formation,  Delaware,  and  Selma  chalk,  Alabama,  of  the 
Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1495). 

Cassidulus  ^quoreus  Morton. 
Plate  XXX,  figures  2a^i. 
Cassidulus  lequoreus  Morton,  1S34,  Synopsis  Organic  Remains  Cretaceous,  p.  76,  PI.  Ill,  fig.  14. 
Cassidulus  xquoreus  Desmoulins,  1837,  Etudes  sur  les  echinides,  p.  146. 
Cassidulus  xquoreus  Lamarck,  1840,  Hist.  Nat.,  vol.  3,  p.  341. 
Cassidulus  xquoreus  Agssiz  and  Desor,  1847,  Catalogue  raisonn^,  p.  141. 
Cassidulus  xquoreus  D'Orbigny,  1847,  Prodrome,  vol.  2,  p.  271. 
Cassidulus  xquoreus  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  244. 

Cassidulus  xquoreus  D'Orbigny,  1853-60,  Paleontologie  fran^aise,  vol.  6,  p.  329,  PI.  CMXXVI,  figs.  6-12. 
Cassidulus  xquoreus  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  290. 
Cassidulus  xquoreum  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  18. 
Cassidulus  xquoreus  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  2. 
Cassidulus  xquoreus  Conrad,  1868,  Geology  of  New  Jersey,  App.  A,  p.  722. 
Cassidulus  xquoreus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Cassidulus  xquoreus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Cassidulus  xquoreus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97.  pp.  68,  69,  PL  XXIX,  figs.  la-i. 
Cassidulus  xquoreus  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Cassidulus  xquoreus  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  293-294,  PL 
XII,  figs.  5-12. 

Determinative  characters. — Test  subpentagonal,  depressed;  upper  surface  convex;  under 
surface  concave,  slightly  rostrated  posteriorly;  apex  forward  of  the  center.  Ambulacra  narrow; 
poriferous  zones  petaloidal  on  the  upper  surface;  contracted  above  the  margin  and  expanded 
again  on  the  lower  surface,  much  narrowed  at  the  peristome.  Interambulacra  wide,  covered 
with  small  perforated  tubercles.  Apical  system  smiiU,  situated  forward  of  the  center.  Peris- 
tome smaU,  \vith  floscelle.     Periproct  supramarginal,  in  short  sulcus. 

Dimensions. — Typical  form:  Length  31.25  milUmeters;  width  28.12  millimeters;  height 
15.6  millimeters. 

Description. — This  typical  Cassidulus,  early  recognized  as  such  by  Morton,  has  a  depressed 
test,  subpentagonal  in  outline.  It  is  longer  in  the  anteroposterior  diameter  than  the  lateral. 
The  upper  surface  is  convex,  with  sharp  marginal  edges,  while  the  lower  surface  is  flat,  with  a 
slight  concavity  toward  the  center.     The  apex  is  somewhat  anterior  to  the  center. 


76  MESOZOIC    ASTD   CEKOZOIC    ECHIXODEEMATA   OF    THE    UNITED    STATES. 

The  ambulacra  are  narrow.  The  poriferous  zones  are  uniserial,  the  poi-es  of  the  upper  part 
of  the  al)oral  surface  arranged  in  petaloldal  form.  At  a  point  varying  in  the  different  areas  from 
one-c^uarter  to  one-third  of  the  distance  from  the  margin  to  the  apical  system  the  zones  are  con- 
tracted and  continue  as  narrow  bands  over  the  margin  and  to  the  vicinity  of  the  peristome,  where 
they  broaden  again  perceptibly,  becoming  finally  much  contracted  at  the  margin  of  the  oral 
opening.  The  pores  are  distinct  in  the  petaloidal  portion  and  in  the  broadened  area  near  the 
peristome  but  in  the  intermediate  contracted  portion  are  small  and  indistinct.  The  interam- 
bulacra  are  broad  and  covered  by  small  perforated  tubercles  with  sunken  areolas. 

The  apical  system  is  composed  of  four  perforated  genital  and  five  small  ocular  plates.  As 
explained  under  the  previous  species,  the  fifth-genital  is  obsolete. 

The  peristome  is  pentagonal  and  surrounded  by  a  well-developed  flosceUe.  The  oral  lobes 
are  very  prominent  and  the  ambulacral  furrows  much  contracted. 

The  periproct  is  situated  in  a  short  sulcus  on  the  upper  surface. 

Related  forms. — This  species  is  separated  from  O.Jlorealis  by  its  more  depressed  and  elon- 
gated form.  From  0.  micrococcus  it  is  separated  by  it^  sharper  apex,  more  angular  margin,  the 
position  of  its  periproct,  and  the  shorter  pore  openings  in  its  outer  rows. 

Localities. — Prairie  Bluff,  Ala.  (type) ;  bluff  east  of  Atlantic  Highlands,  N.  J. 

Geologic  horizon. — Navesink  marl  of  Monmouth  group,  New  Jereey,  and  Ripley  formation, 
Alabama;  Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1475). 

Cassidulus  micrococcus  Gabb. 

Plate  XXXI,  figures  la-i. 

Cassidulus  micrococcus  Gabb,  1860,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  519. 
Cassidulus  micrococcus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Cassidulus  micrococcus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  .52. 
Cassidulus  micrococcus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  69,  70,  PL  XXX,  figs.  la-i. 
Cassidulus  miaococcus  3 dimson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Determinative  characters. — Test  oval,  rounded  anteriorly,  slightly  rostrated  posteriorly; 
upper  surface  convex,  flattened  at  the  apex;  sides  equally  decUning.  Ambulacra  moderately 
broad;  poriferous  cones  petaloidal  on  dorsal  surface;  outer  row  of  pores  slitlike  in  petaloidal 
portion.  Peristome  small,  pentagonal,  with  floscelle.  Periproct  oval,  situated  high  on  upper 
surface,  in  long,  narrow  sulcus. 

Dimensions. — Length  45  millimeters;  width  42  millimeters;  height  21.5  mdUmeters. 

Description. — This  species  has  a  distinctly  oval  form,  -wader  posteriorly.  The  upper  surface 
is  elevated  at  the  margin  but  somewhat  flattened  at  the  apex.  The  sides  decline  very  nearly 
equally.  The  base  is  flattened,  with  a  slight  concavity  at  the  peristome.  The  posterior  margin 
is  truncated  and  slightly  rostrated. 

The  ambulacra  are  rather  broad,  contracted  about  one-quarter  of  the  distance  from  the 
ambitus  to  the  apex,  and  narrowed  nearly  to  the  peristome,  where  they  are  again  broadened  to 
form  indistinct  phylloidal  areas.  The  pores  are  slitlike  in  the  outer  rows  of  the  ])etaloidal 
portion. 

The  interambulacral  plates  are  covered  with  minute  tubercles,  with  sunken  areolas,  that 
increase  in  size  and  number  of  the  oral  surface. 

The  apical  system  is  situated  slightly  in  front  of  the  upper  surface,  in  a  long,  narrow,  and 
deep  sulcus. 

Related  forms. — A  comparison  of  tlris  species  with  Cassidulus  sequoreus,  as  made  also  by  Gabb 
in  his  original  description,  show^s  that  it  is  much  larger  and  more  oval,  and  that  its  i:)eriproct  is 
situated  higher  and  in  a  deeper  and  longer  sulcus,  and,  furthermore,  that  the  pores  of  the  outer 
row  in  its  petaloidal  portion  are  elongated  and  slitlike. 

Locality. — Eufaula,  Ala. 

Geologic  horizon. — Ripley  formation,  Upper  Cretaceous. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1480). 


CRETACEOUS   ECHINODEEMATA.  77 

Cassidui.us  subquadeatus  Conrad. 

Plate  XXXI,  figures  2a-g. 

Cassidulus  subquadratus  Conrad,  1860,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  4,  p.  291,  PI.  XLVII,  fig.  1!). 

Cassidulus  suhquadratus  A.  Agassiz,  1883,  Mus.  Comp.  Zool.  Mem.,  vol.  10,  p.  90. 

Cassidulus  suhquadratus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Cassidulus  subquadratus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Cassidulus  subquadratus  Clark,  1893,  U.  S.  Cxeol.  Siu^ey  Bull.  97,  pp.  70,  71,  PI.  XXXI,  figs.  la-h. 

Cassidulus  subquadratus  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Cassidulus  subquadratus  Slocum,  1909,  Field  Mus.  Nat.  Hist.  Pub.  134,  Geol.  ser.,  vol.  4,  No.  1,  pp.  5,  6. 

Determinative  characters. — Test  subquadrate  to  subpentagonal,  hemispherical;  sides  equally 
decUning,  upper  surface  convex;  lower  surface  concave;  posterior  margin  truncated  and  ros- 
trated. Poriferous  zones  broadly  petaloidal  on  upper  two-thirds  of  the  dorsal  surface;  sharply 
contracted  at  lower  margin  of  petaloidal  areas.  Peristome  small,  pentagonal,  with  well-defined 
floscelle.     Apical  system  large,  shghtly  anterior  to  the  center.     Periproct  round,  in  deep  sulcus. 

Dimensions. — Length  56.5  millimeters;  width  53  millimeters,  height  28  milHmeters. 

Description. — This  remarkably  synmietrical  Cassidulus  has  a  nearly  hemispherical  form. 
In  outhne  it  is  nearer  subpentagonal  than  subquadrate,  owmg  to  the  rostrated  character  of  the 
posterior  margin,  which  is  at  the  same  time  truncated.  The  anterior  margin  is  rounded.  The 
lateral  edges  are  nearly  parallel,  though  somewhat  more  approximated  anteriorly.  The  apex  is 
shghtly  forward  of  the  center. 

The  ambulacra  are  moderately  wide  in  the  petaloidal  portion,  narrow  beyond.  The  porif- 
erous zones  are  composed  in  the  petaloidal  portion  of  an  iimer  row  of  small,  nearly  circular  pores 
and  of  an  outer  row  of  obhque  sUtUke  openings.  The  pores  of  each  pair  are  united  by  a  shallow 
furrow.  Beyond  the  petaloidal  areas  the  narrow  plates  of  those  portions  give  place  to  broad 
plates,  each  with  a  pair  of  small,  round  pores  in  the  lower  and  outer  corner.  In  the  vicinity  of 
the  peristome  the  poriferous  zones  expand  and  the  pores  increase  in  size,  though  apparently 
reduced  in  number.     The  last  pair  of  plates  are  much  contracted. 

The  interambulacra  are  wide.  The  plates  are  covered  -vvitli  minute  tubercles  with  depressed 
areolas,  which  become  larger  and  more  prominent  on  the  lower  surface. 

The  apical  system  is  large,  composed  of  four  perforated  genital  and  five  ocular  plates.  The 
fifth  genital  is  apparently  obsolete. 

The  peristome  is  small,  pentagonal,  and  surrounded  by  a  weU-developed  floscelle.  The 
periproct  is  round  and  is  situated  high  above  the  margin,  in  a  deep  sulcus,  that  becomes  narrower 
and  shallower  toward  the  ambitus. 

Related  forms.— 1h\s  species  is  most  closely  related  to  Cassidulus  suhconicus,  but  the  latter 
is  much  more  elevated  and  has  its  periproct  situated  higher  and  in  a  less  depressed  sulcus. 

Locality. — Near  Holly  Springs,  Miss. 

Geologic  Jiorizon. — Ripley  formation.  Upper  Cretaceous. 

Collection. — U.  S.  National  Museum  (31200). 

Cassidiilus  subconicus  Clark. 

Plate  XXXII,  figures  la-k. 

Cassidulus  subconicus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 

Cassidulus  subconicus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Cassidulus  subconicus  Clark,  1893,  U.  S.  Geol.  Siu-vey  Bull.  97,  pp.  71,  72,  PI.  XXXII,  figs.  la-k. 

Determinative  characters. — Test  subcorneal;  margin  subpentagonal,  truncated  and  rostrated 
posteriorly;  apex  anteriorly  placed.  Ambulacra  broad  in  petaloidal  areas.  Apical  system 
large,  anteriorly  situated.  Peristome  subcircular,  with  very  prominent  floscelle.  Periproct 
large,  situated  high  on  upper  surface,  in  shaUow  sulcus. 

Dimensions. — Length  47  milhmeters;  width  43  miUimeters;  height  27.5  milhmeters. 

Description. — The  tost  is  subcorneal.  In  marginal  outline  it  is  subpentagonal,  the  pos- 
terior border  more  or  less  rostrated  and  clearly  truncated.  The  apex  is  slightly  forward  of  the 
center,  giving  a  somewhat  sharper  slope  to  the  anterior  portion  of  the  test  than  to  the  posterior. 
39S00°— 15 6 


78  MESOZOIC    AND    CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

The  ambulacra  are  broad  in  the  pctaloidal  portion,  beyond  wliich  they  are  narrowed.  At 
the  margin  thej'  again  acquire  considerable  ■n^idth  but  gradually  contract  beyond,  although 
expanded  for  a  short  distance  in  the  phyUoidal  area  near  the  peristome.  At  the  peristome  the 
final  pair  of  plates  is  highly  attenuated.  The  pores  of  the  outer  rows,  in  both  the  petaloidal  and 
phyloidal  areas,  are  in  a  marked  degree  elongated.  In  the  intermediate  portion  of  the  column 
they  are  small  and  indistinct. 

The  interambulacra  are  more  prominent  than  the  ambulacra,  which  are  shghtly  depressed. 
The  surface  is  covered  ^vith  minute  tubercles  and  a  microscopic  granulation. 

The  apical  system  is  large,  subcircular,  and  surrounded  by  a  very  prominent  floscelle.  The 
periproct  is  large,  circular,  and  is  situated  high  above  the  margin  in  a  shallow  sulcus. 

Related  forms. — C.  subconicus  is  closely  related  to  C  subquadratus  but  is  separated  from  it 
by  its  liigli  subconical  test,  more  elevated  periproct,  and  shallow  anal  sulcus. 

Locality. — Dumas,  Miss. 

Geologic  horizon. — Ripley  formation,  Upper  Cretaceous. 

Collection.— v.  S.  National  Museum  (20264). 

Cassidulus   porrectus  Clark. 

Plate  XXXII,  figures  2a-b;  Plate  XXXIII,  figures  la-f. 

Cassidulus  porrectus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  7G. 
Cassidulus  porrectus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Cassidulus  porrectus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  72,  73,  PL  XXXIII,  figs,  la-b,  PI.  XXXIV,  figs,  la-b., 
PI.  XXXV,  figs.  la-d. 

Determinative  characters. — Test  very  large,  subcircular,  oval,  depressed;  upper  surface  con- 
vex; lower  surface  concave;  broader  posteriorly  than  anteriorly;  apex  forward  of  the  center. 
Ambulacra  broad.  Interambulacra  tliickly  covered  with  minute  tubercles.  Apical  system 
small,  forward  of  the  center.  Peristome  large,  subconical,  ^vith  prominent  flosceUe.  Periproct 
supramarginal,  in  short  shallow  sulcus. 

Dimensions. — Length  99.6  milhmeters;  width  97.5  milhmeters;  height  44.5  miUimeters. 

Description. — This  very  large  Cassidulus  has  an  irregularly  oval,  depressed  test,  that  is  sub- 
circular  in  marginal  outline.  The  width  is  equal  to  the  length  but  is  greatest  in  the  posterior 
portion,  so  that  the  margin  appears  contracted  anteriorly.  The  apex  is  some  distance  foi-ward  of 
the  center  and  shghtly  flattened.     The  posterior  margin  is  feebly  trimcated. 

The  ambulacra  are  wide;  the  contractions  below  the  petaloidal  region  and  above  the  phyl- 
loidal  continue  for  short  distances,  while  the  lowest  pair  of  plates  in  the  colunm  bordering  the 
peristome  are  long  and  greatly  attenuated.  The  pores  of  the  outer  rows  are  sUthke  in  form  and 
obhquely  placed. 

The  interambulacra  are  prominent ;  the  plates  are  covered  with  numerous  small  tubercles, 
with  depressed  areolas,  which  are  larger  and  more  prominent  on  the  under  than  the  upper  surface. 
The  apical  system  is  small  and  is  placed  forward  of  the  center. 

The  peristome  is  large,  subcircular,  with  very  promment  floscelle.  The  oral  lobes  project 
far  beyond  the  level  of  the  base  and  are  separated  by  deep  ambulacral  furrows. 

The  periproct  is  large,  oval,  and  is  situated  at  the  head  of  a  short,  narrow  sulcus. 

Related  forms. —  C.  porrectus  is  from  its  size,  form,  and  details  of  structure  readilj^  separated 
from  the  other  species  of  Cassidulus  described  from  the  American  and  European  Cretaceous. 

Locality. — Eufaula,  Ala. 

Geologic  hori.zon. — Ripley  formation,  Upper  Cretaceous. 

Collection. — U.  S.  National  Museum  (21890). 


CRETACEOUS  ECHINODERMATA.  79 

Cassidulus  stantoni  Clark. 

Plate  XXXIII,  figures  2a-d. 

Cassidulus  stantoni  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  76. 
Cassidulus  stantoni  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Cassidulus  stantoni  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  73,  PL  XXXV,  figs.  2a-d. 

Determinative  clmracters. — Test  small,  subovate,  elevated;  upper  surface  convex,  lower 
surface  concave;  apex  foi-ward  ofthe  center.  Ambulacra  verj-  narrow.  Apical  sj^stem  small, 
forward  of  the  center.  Peristome  small,  with  fioscelle.  Periproct  high  above  margin,  in  long, 
narrow,  and  deep  sulcus. 

Dimensions. — Length  15  millmietei-s;  width  14  millimeters;  height  6.5  millimeters. 

Description. — This  minute  Cassidulus  has  a  subovate  test,  an  elevated  convex  upper  sur- 
face, and  a  concave  lower  surface.  It  is  broader  posteriorly  than  anteriorly,  and  its  posterior 
margin  is  truncated.     The  apex  is  situated  slightly  anterior  to  the  center  of  the  upper  surface. 

The  ambulacra  are  very  narrow.  The  petaloidal  portion  but  slightly  exceeds  the  remainder 
in  width,  which  is  nearly  equal  throughout.     The  phylloidal  region  is  feebly  outlined. 

The  mterambulacra  are  broad,  but  the  poor  state  of  preservation  of  the  specmiens  renders 
it  unpossible  to  determine  all  the  details  of  structure. 

The  apical  system  is  small  and  forward  of  the  center,  but  not  sufficiently  well  preserved 
to  distinguish  the  mdividual  plates.  The  peristome  is  small  and  surrounded  by  a  feeble  fios- 
celle. The  periproct  is  round  and  situated  high  above  the  margm,  at  the  head  of  a  narrow  deep 
sulcus. 

Related  forms. — C.  stantoni  is  quite  unlike  any  other  representative  of  this  genus  from  Ameri- 
can strata  and  can  not  be  readily  associated  with  any  European  species. 

Locality. — Muddy  Creek,  Huerfano  County,  Colo. 

Geologic  horizon. — Colorado  group.  Upper  Cretaceous. 

Collection. — U.  S.  National  Museum  (20260). 

Cassidulus  intekmedius  Slocum. 

Plate  XXXIV,  figures  la-f. 
Cassidulus  intermedius  Slocum,  1909,  Field  Mus.  Nat.  Hist.  Pub.  134,  Geol.  ser.,  vol.  4,  No.  1,  pp.  6,  7,  PI.  I,  figs.  1-6. 

Determinative  clmracters. — Test  oval,  depressed,  rounded  anteriorly,  slightly  rostrated  pos- 
teriorly. Apex  excentric  anteriorly.  Ambulacra  narrow.  Peristome  large,  slightly  in  front 
of  center  of  ventral  surface.  Periproct  on  upper  surface,  about  one-thu-d  of  the  distance  from 
the  apex  to  the  margin,  in  broad  deep  sulcus. 

Dimensions. — Type  specmien:  Length  25.6  millimeters;  width  22.7  millimeters;  height  9.6 
millimeters. 

Slocum  says: 

Description. — Test  oval,  greatest  width  posterior  to  the  center;  rounded  anteriorly,  slightly  rostrated  posterforly- 
dorsal  surface  convex,  apex  excentric  anteriorly  and  inflated,  sides  declining  about  equally  towards  the  maroins  which 
are  slightly  inflated ;  the  peristomal  concavity  occupying  more  than  half  of  the  central  stirface.  Ambulacra!  areas  nar- 
row and  flush,  poriferous  zones  subpetaloidal  on  the  upper  part  of  the  dorsal  sm-face  to  a  point  varyino-  in  the  different 
areas  from  about  one- third  to  nearly  one-half  the  distance  from  the  margin  to  the  apical  system;  the  zones  are  then  con- 
tracted and  continue  as  naiTOW  bands  over  the  margin  to  the  vicinity  of  the  peristome,  where  they  abruptly  widen,, 
and  gain  narrow  to  the  peristome  forming  a  floscelle.  The  pores  are  distant  and  paired  on  the  petaloid  portion  and  in 
the  floscelle;  on  the  narrow  connecting  portions  they  are  single,  small  and  indistinct.  In  the  petaloid  areas  the  pores 
of  the  outer  rows  are  sUtlike,  those  of  the  inner  row  round  and  smaller;  each  pair  is  connected  by  a  groove.  Inter- 
ambulacral  areas  composed  of  large  plates,  the  plates  nearest  the  peristome  in  each  area  inflated  forming  the  bourrelets. 
Dorsal  surface  covered  with  small  crowded  tubercles  with  slightly  sunken  areoles,  the  tubercles  on  the  ventral  surface 
rapidly  increasing  in  size  and  distance  apart  as  they  approach  the  peristome.  A  wide,  longitudinal  median  band  extends 
from  near  the  anterior  margin  through  the  floscelle  to  the  posterior  margin.  This  band  is  without  tubercles  and  the 
surface  is  smooth  except  where  it  passes  through  the  floscelle.  The  apical  system  in  the  type  specimen  is  too  incomplete 
for  detailed  description,  but  appears  similar  to  other  species  of  this  genus.  The  peristome  is  situated  slightly  in  front  of 
the  center  of  the  ventral  surface,  pentagonal,  surrounded  by  a  well-marked  floscelle,  the  bourrelets  large  and  prominent, 


80  MESOZOIC    AND   CENOZOIC    ECHINODEEMATA   OF    THE    UNITED    STATES. 

the  phyllodes  very  narrow  as  they  reach  the  peristome  and  situated  in  grooves.  The  periproct  is  elongat«d  longitudi- 
nally and  situated  on  the  dorsal  surface  about  one-third  the  distance  from  the  posterior  margin  to  the  apex  in  a  deep 
groove. 

Related  forms. — In  general  form  this  species  resembles  ('.  a:quoreus,  but  is  not  so  high  in  proportion  to  its  length,  the 
periproct  is  somewhat  higher,  the  pores  in  the  outer  rows  of  the  petaloid  portions  are  slitUke  instead  of  round,  and  the 
expansions  of  the  phyllodes  are  wider.  C  intermedius  resembles  C.  micrococcus  in  the  sLitlike  pores  of  the  outer  rows 
of  the  petaloid  areas  and  in  the  expansion  of  the  phyllodes,  but  the  position  of  the  pores  in  these  expansions  is  more 
like  those  of  C.  sequoreiis.  The  position  of  the  perijjroct  is  midway  between  that  of  C.  micrococcus  and  C.  aquoreus,  the 
size  and  shape  of  the  test  is  quite  unlike  C.  micrococcus  and  the  extension  of  the  longitudinal  median  band  in  front  of 
the  peristome  on  the  ventral  surface  does  not  apjjear,  from  the  description  and  figures,  to  occur  in  either  of  the  other 
species.  The  name  adopted  for  this  species  refers  to  the  characters  intermediate  between  C.  sequoreus  and  C.  micrococ- 
cus which  the  species  exhibits. 

Locality. — Nccar  the  southern  edge  of  the  village  of  Pontotoc  (Slocum),  Miss. 
Geologic  horizon. — Ripley  formation,  Upper  Cretaceous. 
Collection.— Field  Museum  of  Natural  History  (P  10346). 

Cassidulus  hemispheeicus  Slocum. 

Plate  XXXIV,   figures  2a-c. 
Cassidulus  hemisphericvs  Slocum,  1909,  Field  Mus.  Nat.  Hist.  Pub.  134,  Geol.  ser.,  vol.  4,  >V.  1,  pp.  7,  8,  PI.  I,  figs.  7-9. 

Determinative  characters. — Test  subhemispherical,  elevated,  marghis  angular,  lower  sm-face 
flat.     Ambulacra  wide.     Peristome  nearly  central.     Periproct  supramarginal. 

Dimensions. — Type  specimen:  Length  34.7  niUlimeters ;  width  26.7  millimeters;  height 
19.5  millimeters.  Allowing  for  the  lateral  crushing  it  is  probable  that  the  length  and  width, 
were  origmally  about  32  mUluneters  and  29  millimeters,  respectively. 

Description. — Slocum  says : 
Test  subhemispherical  with  its  transverse  diameter  somewhat  shorter  than  the  longitudinal,  sides  arcuate,  margins 
an"-ular,  ventral  siu-face  flat  or  nearly  so.  Ambulacral  areas  wide,  subpetaloidal  on  the  top  of  the  dorsal  surface,  not 
closed  distally,  petals  subequal  in  length,  extending  aljout  halfway  from  the  apex  to  the  margin,  slightly  convex;  from 
the  distal  end  of  the  petals  the  ambulacral  areas  are  continued  as  a  band  wliich  gradually  increased  in  width  from  the 
petal  to  the  margin,  most  of  the  way  being  wider  than  the  petal.  On  the  ventral  surface  the  bands  slightlj'  narrow  to 
the  floscelle.  The  floscelle  is  not  well  preserved  in  the  type  specimen,  but  enough  is  preserved  to  determine  that  the 
bovu-relets  are  prominent  and  that  the  phyllodes  are  in  grooves.  The  apical  system  is  central  but  the  form  of  the  various 
plates  of  which  it  is  composed  can  not  be  determined.  The  interambulacral  areas  are  about  equal  in  size.  They  form 
an  acute  angle  near  the  apex  and  rapidly  expand  to  the  margin,  the  plates  being  comparativel)^  large.  AU  the  plates 
of  the  dorsal  siu-face,  with  the  exception  of  those  of  the  petals,  are  marked  by  prominent  lines  subparallel  to  the  edge 
of  the  plates.  These  lines  are  farther  apart  on  the  lateral  edges  than  on  the  proximal  and  distal  edges.  They  appear 
to  be  lines  of  growth.  The  middle  portion  of  the  plates  within  this  series  of  lines  is  inflated,  so  that  in  the  small  plates 
of  the  interambulacral  areas,  near  the  apex,  the  centers  of  the  plates  appear  as  prominent  nodes.  These  middle  portions 
of  the  plates  are  free  from  tubercles,  but  the  parts  of  the  plates  covered  by  the  parallel  lines  and  the  plates  of  the  petals 
are  covered  with  minute  tubercles  closely  crowded  together.  The  lines  are  much  less  prominent  on  the  plates  of  the 
ventral  surface  and  the  tubercles  are  larger,  with  slightly  sunken  areoles,  and  more  evenly  distributed  over  the  siu-face, 
except  on  the  longitudinal  median  band,  which  extends  from  the  peristome  to  the  posterior  margin.  The  peristome  is 
situated  at  the  center  of  the  ventral  siurface,  surrounded  by  a  floscelle,  the  bourrelets  are  prominent,  and  the  phyllodes 
are  depressed  and  contracted  into  narrow  grooves  where  they  reach  the  peristome.  The  periproct  is  supramarginal, 
but  its  form  and  exact  position  are  unknown,  because  that  portion  of  the  posterior  interambulacral  area  near  the  margin 
is  missing. 

Locality. — The  "white  gullies"  on  the  Patterson  farm,  about  3  miles  south  of  Pontotoc, 
Miss. 

Geologic  horizon. — Ripley  formation,  Upper  Cretaceous. 
Collection.— Yield  Museum  of  Natural  History  (P  10347). 

Cassidulus  conoideus  Clark,  n.  sp. 
Plate  XXVII,  figures  3a-d. 

Determinative  characters. — Test  moderate,  nearly  circular,  mflated  above,  flat  below. 
Apical  system  excentric  anteriorly.  Ambulacra  nearly  sunUar,  subpetaloid.  Peristome  excen- 
tric  forward.     Periproct  supramarguial  in  poorly  defined  groove. 

Dimensions.— Length.  31.5  millimeters;  width  32  millimeters;  height  28  millimeters. 


CRETACEOUS  ECHINODERMATA.  81 

Description. — This  species  has  a  tost  of  moderate  size,  nearly  circular  and  much  elevated. 
The  apex  is  near  the  center  of  the  upper  surface.  The  upper  surface  is  convex,  the  lower  nearly 
flat. 

The  ambulacra  are  wide,  nearly  similar,  distinctly  petaloidal  above.  The  interambulacra 
are  prominent,  projecting  slightly  above  the  ambidacra. 

The  peristome  is  of  small  size  and  excentric  forward.  The  periproct  is  small,  supramar- 
ginal  and  located  in  a  very  poorly  defined  groove.  The  material  of  the  test  has  been  destroyed, 
only  a  cast  remaining. 

Locality. — Pataula  Creek,  Clay  County,  Ga. 

Geologic  horizon. — Ripley  formation.  Upper  Cretaceous. 

Collection.— v.  S.  National  Museum  (31199). 

Cassidulus  abruptus  Conrad. 

Cassidulus  abruptus  Conrad,  1860,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  4,  p.  291. 
Casnidulus  abruptus  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  90. 
(?)  Cassidulus  abruptus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
(?)  Cassidulus  abruptus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  92. 

This  species,  originally  described  by  Conrad  in  1860,  but  not  figured,  has  not  been  recog- 
nized in  material  examined  by  the  writer,  so  that  its  relations  to  the  other  forms  described  are 
not  known. 

Locality. — Tippah  County,  Miss. 

Geologic  horizon. — Ripley  formation.  Upper  Cretaceous. 

Collection. — Unknown. 

?  Cassidulus  subangulatus  (Emmons). 

Gonioclypeus  subangulatus  Emmons,  1858,  North  Carolina  Geol.  Survey  Rept.,  p.  309,  figs.  242,  243. 
Gonioclypeus  subangulatus  Conrad,  1866,  Check  list,  p.  31. 

This  species,  which  is  described  from  the  "Eocene,  Wadsworth  marl.  Craven  County," 
N.  C,  by  Emmons  is  probably  a  Cretaceous  form  and  if  the  strata  in  which  it  was  found  are 
Eocene  was  doubtless  mechanically  transported  from  older  deposits.  It  is  apparently  identical 
with  C.  suhquadratus  Conrad,  but  as  its  type  form  is  unknown  and  no  further  material  has  been 
found  it  seems  wiser  to  maintain  the  separation  of  the  two  species  until  more  positive  data  are 
secured. 

Locality. — Craven  County,  N.  C. 

Geologic  horizon. — Peedee  sand  (?),  Upper  Cretaceous. 

Collection. — Unkno  wn . 

Suborder  STERNATA. 

Family  ECHINOCORYTHID.'E. 

Genus  ANANCHYTES  Mercati. 

Ananchytes  ovalis  C'lark. 

Plate  XXXV,  figures  la-h. 

Ananchytes  ovalis  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Ananchytes  ovalis  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  74,  75,  PI.  XXXVI,  figs.  la-h. 

Ananchytes  ovalis  Weller,  1907,  Cretaceous  paleontology  of    New  Jersey:   Geol.   Survey  New   Jersey,  p.  295,  PI. 
XIII,  figs.  1-8. 

Determinative  characters. — Test  medium  sized,  subovate  cordate;  contracted  posteriorly; 
upper  surface  convex;  lower  surface  flat.  Apical  system  elongated,  consisting  of  four  perfo- 
rated genital  and  five  ocular  plates  situated  slightly  forward  of  the  center.  Peristome  near  the 
anterior  margin.     Periproct  oval,  situated  on  a  slight  protuberance  of  the  posterior  margin. 


82  MESOZOIC    AXD   CENOZOIC    ECHINODEEMATA   OF    THE    UNITED    STATES. 

Dimensions. — Length  43.75  millimeters;  width  37.5  millimeters;  height  31.25  millimeters. 

Description. — The  specimens  of  this  species  collected  by  the  writer  are  remarkably  well  pre- 
served and  admit  of  the  determination  of  all  the  essential  features.  The  test  is  in  lateral  outline 
subovate,  though  somewhat  cordate  in  form  when  viewed  from  above  or  below.  A  marked  pro- 
tuberance is  present  on  the  posterior  margin  that  appears  as  a  slight  ridge  on  the  lower  suiiace 
between  the  peristome  and  periproct.  The  upper  surface  is  convex.  The  sides  are  full  and 
rounded  at  the  ambitus.  The  base  is  nearly  fiat,  with  the  exception  of  the  slight  ridge  and 
depressed  peristome. 

The  ambulacra  are  wide  and  straight,  attaining  their  greatest  width  just  above  the  ambitus. 
The  pores  are  oval,  and  those  of  each  pair  are  placed  toward  the  ambitus  at  an  angle  to  one 
another.  The  surface  of  both  the  ambulacral  and  interambulacral  plates  is  covered  by  small 
tubercles,  between  which  are  numerous  microscopic  granules.  The  apical  system  is  elongated. 
The  four  genital  plates  are  large  and  distinctly  perforated.  The  anterior,  right-hand  genital 
plate,  which  serves  as  the  madreporite,  is  much  larger  than  any  of  the  others,  being  several  times 
the  size  of  the  anterior  left-hand  genital,  with  which  it  is  in  contact.  The  posterior  genitals  are 
very  nearly  of  equal  size. 

The  peristome  is  transvereely  oblong  and  situated  near  the  anterior  margin.  The  periproct 
is  oval  and  situated  on  a  marked  protuberance  on  the  posterior  margin. 

Locality. — Vincentown,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group.  Upper  Cretaceous. 

Collection. — Johns  Hopkins  University  (T  3011). 

Ananchytes  texana  Cragin. 

Plate  XXXV,  figures 2a-c;  Plate XXXVI,  figures  la-b. 

Ananchytes  texana  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,'pp.  145,  146,  PI.  XXVI,  figs.  1,  2,  PI.  XXV, 
fig.  12. 

Determinative  characters. — Test  large,  liigh,  oval  in  marginal  outline,  roimded  anteriorly, 
narrowed  posteriorly;  upper  surface  convex,  lower  surface  flat;  ambulacra  flush,  nearly  alike, 
apetalous  pair  of  pores  more  strongly  developed  on  upper  surface;  interambulacra  with  large 
plates  covered  with  few  primary  tubercles  and  many  granules;  peristome  far  in  front;  periproct 
well  forward  on  lower  surface. 

Dimensions. — ^Length  107  millimeters;  width  87  millimeters;  height  68  millimeters. 

Description. — Cragin  says : 

Large  conico-hemispherical  as  seen  from  the  side;  plan  ovate,  wider  anteriorly;  peristome  of  moderate  size,  trans- 
verse, oblong-reniform,  the  anterior  lip  and  immediately  contiguous  surface  deeply  and  abruptly  depressed,  the 
remainder  of  the  interior  surface  slightly  depressed,  the  depression  being  posteriorly  parted  by  a  gentle  median  undu- 
lation that  includes  the  periproct  and  becomes  gradually  obsolete  a  short  distance  in  advance  of  it;  periproct  infra- 
marginal  and  relatively  smaller  than  in  most  (if  not  all)  other  known  species  of  the  genus,  rather  narrowly  ovate  and 
posteriorly  more  or  less  pointed;  anterior  ambulacrum  about  two-thirds  as  wide  as  either  of  the  adjacent  interambula- 
cra, ambulacral  plates  very  numerous  and  narrow,  averaging  about  a  millimeter  in  -ividth  on  the  greater  part  of  the  zone; 
the  pores  rounded  but  usually  more  or  less  transversely  elongated,  the  line  connecting  the  pores  of  one  pair  being  hori- 
zontal except  in  the  case  of  a  few  of  the  lower  pairs;  surface  nearly  even,  the  principal  tubercles  rather  small  and  not 
very  prominent. 

Locality. — Two  and  one-half  miles  northwest  of  D'Haniss,  on  Seco  Creek,  Medina  County, 
Tex.  (type);  White  Cliffs,  Ark. 

Geologic  horizon. — Austin  chalk  and  Annona  chalk,  Upper  Cretaceous. 
Collections. — Geological  Survey  of  Texas;  Johns  Hopkins  University. 


CRETACEOUS   ECHINODEEMATA.  83 

Genus  CABDIASTEB  Forbes. 
Caediaster  cinctus  (Morton). 

Plate  XXXVI,  figures  2a-li. 

Spatangiis  sp.  Morton,  1829,  Acad.  Nat.  Sci.  Pliiladelphia  Jour.,  1st  ser.,  vol.  6,  p.  122. 
Ananchytes  sp.  Morton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.  17,  p.  287. 

Ananchijlts  cinctus  Morton,  1830,  Acad.  Nat.  Sci.  Pliiladelphia  Jour.,  1st  ser.,  vol.  6,  p.  200. 
AnanchytesJimbriatusMoTton,  1830,  Acad.  Nat.  Sci.  Philadelpliia  Jour.,  1st  ser,,  vol.  6,  p.  200. 
Anmichytes  cinctus  Morton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.  18,  p.  246,  PI.  Ill,  fig.  7. 
Ananchytes  fiinbriatusMorton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.  18,  p.  245,  PI.  Ill,  fig.  9. 
Ananchytes  cinctus  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  78,  PI.  Ill,  fig.  19. 
Ananchytes  fimbriate  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  pp.  77,  79,  PI.  Ill,  fig.  20. 
Holaster  cinctus  Agassiz  and  Desor,  1840,  Catalogue  systematique,  p.  1. 
Holaslcr  cinctus  Agassiz  and  Desor,  1847,  Catalogue  rais  jnne,  p.  133. 
Sola ster  Jimbriatus  AgSLSsiz,  1847,  Catalogue  raisonne,  p.  141. 
Holaster  cinctus  D'Orbigny,  1847,  Prodrome,  vol.  2,  p.  269. 
Holaster fimbriatus  D'Orbigny,  1847,  Prodrome,  vol.  2,  p.  269. 
Holaster  cinctus  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  593. 
Ananchytes  fimbriatus  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  70. 
Cardiaster  cinctus  Bronn,  1853-1856,  Lethaea  geognostica,  vol.  2,  pt.  5,  p.  205. 

Cardiaster  cinctus  D'Orbigny,  1853-1860,  Palfontologie  frangaise,  vol.  6,  p.  147;  PI.  CMXCV,  fig.  4. 
Cardiaster  fimbriatus  D'Orbigny,  1853-1860,  Pal^ontologie  frangaise,  vol.  6,  p.  147 ;  PI.  CMXCV,  fig.  3. 
Cardiaster  cinctus  (Cardiaster  fimbriatus)  Desor,  1858,  Synopsis  desecbinides  fosailes,  p.  346. 
Ananchytes  cinctus  Gabb,  1859,  Cat.  .Invert.  Fossils  Cretaceous,  p.  18. 
Ananchytes  fimbriatus  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  18. 
Holaster  cinctus  Credner,  1870,  Deutsche  geol.  Gesell.  Zeitschr.,  vol.  22,  p.  218. 
Holaster  cinctus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Cardiaster  cinctus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Cardiaster  cinctus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  75,  76,  PI.  XXXVII,  figs.  la-h. 
Cardiaster  fimbriatus  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 
Cardiaster  cinctus  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelpliia  Proc,  vol.  57,  p.  7. 

Cardiaster  cinctus  Weller,  1907,  Oetaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  296-297,  PI.  XVI, 
figs.  1-8. 

Determinative  characters. — Test  large,  cordate,  distinctly  grooved  anteriorly;  contracted 
posteriorly;  upper  surface  convex;  lower  surface  flat.  Ambulacra  wide.  Apical  system  much 
elongated,  consisting  of  four  perforated  genital  and  five  ocular  plates  situated  slightly  forward 
of  the  center.  Peristome  near  the  anterior  margin.  Periproct  oval,  situated  on  the  truncated 
posterior  margin. 

Dimensions. — Length  30  to  60  millimeters;  width  25  to  55  millimeters;  height  20  to  30 
millimeters. 

Description. — This  species,  which  is  among  the  earliest  of  the  Echinoid  forms  recognized 
from  American  Cretaceous  strata,  is  distinctly  cordiform,  with  a  pronounced  groove  on  the 
anterior  face  that  is  occupied  by  the  unpaired  ambulacrum.  Opposite  thereto  is  a  slight  ridge 
at  the  central  suture  of  the  unpaired  posterior  interambulacnim  which  is  suddenly  terminated 
by  the  nearly  vertically  truncated  surface  of  the  posterior  margin.  The  sides  decline  equally  to 
the  ambitus,  giving  an  oval  outline  to  the  vertical  lateral  section.  The  lower  surface  is  nearly 
flat,  with  the  exception  of  the  slight  depressions  directly  at  the  mouth  edges  and  the  elevated 
area  extending  from  the  center  of  the  base  to  the  posterior  margin. 

The  ambulacra  are  wide,  apetaloid,  and  separated  at  the  apex.  The  anterolateral  pair  are 
bent  backward  in  their  upper  part,  beyond  which  they  extend  straight  to  the  margin.  The 
postero-lateral  pair  are  bent  somewhat  forward,  after  which  they  ext«nd  straight  over  the  margin. 
The  single  ambulacrum  is  situated  in  the  deep  anterior  sulcus.  The  pores  of  the  paired  ambu- 
lacra consist,  in  the  upper  portion  of  the  columns,  of  oblique  oval  openings  united  by  furrows 
while  lower  do^vn  they  become  small  and  often  indistmct.  In  the  unpaired  ambulacrum  the 
pores  are  extremely  small. 

The  surface  of  the  interambulacral  as  well  as  of  the  ambulacral  plates  is  covered  with  fine 
grannies,  among  which  are  irregularly  scattered  numerous  small  perforated  tubercles. 


84  MESOZOIC   AND   CENOZOIC    ECHINODEKMATA   OF    THE    UNITED   STATES. 

The  apical  system  is  narrow,  elongated.  The  four  perforated  genital  plates  are  disposed  in 
pairs,  between  which  two  of  the  five  ocular  plates  are  situated.  Forming  the  posterior  portion 
of  the  disk  are  two  more  ocular  plates,  while  the  fifth  plate  comprises  the  anterior  part.  The 
ambulacral  areas  are  on  this  account  separated  at  their  apices. 

The  i^eristome  is  transversely  oblong  and  is  situated  near  the  anterior  margin  of  the  base. 
The  periproct  is  oval  and  situated  on  the  truncated  surface  at  the  posterior  margin  of  the  test. 

Localities. — ^Vincentown  and  Timber  Creek,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collections. — Academy  of  Natural  Sciences  of  Philadelphia  (1485) ;  American  Museum  of 
Natural  History,  New  York. 

Cardiaster  smocki  Clark. 

Plate  XXXVI,  figures  3a-c. 

Cardiaster  smocki  Clark,  1907;  Weller,   Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  p.  298,  PI. 
XIII,  figs.  9-11. 

Determinative  characters. — Test  cordiform,  elevated,  with  deep  anterior  sulcus;  upper  sur- 
face convex;  lower  surface  flat.  Ambulacra  wide.  Apical  system  elongated.  Peristome  near 
the  anterior  margin. 

Dimensions. — Length  25  millimeters;  width  23  millimeters;  height  14  millimeters. 

Description. — The  test  is  small,  distiactly  elevated,  with  strongly  convex  upper  surface. 
The  anterior  ambulacral  sulcus  is  very  pronounced,  and  the  opposite  ridge  in  the  unpaired  pos- 
terior interambulacrum  is  well  sliowTi  but  is  sharply  cut  off  by  the  nearly  vertically  truncated 
surface  of  the  posterior  margin.  The  sides  slope  rapidly  to  the  ambitus,  which  is  sharp  and  cor- 
date in  outline.     The  lower  surface  is  nearly  flat. 

The  ambulacra  are  wide,  apetaloid,  and  well  separated  at  the  apex.  The  anterolateral  pair 
are  bent  backward  above,  beyond  which  they  extend  straight  to  the  ambitus.  The  postero- 
lateral pair  are  bent  slightly  forward,  beyond  which  they  continue,  in  a  straight  liae  over  the 
margin.     The  unpaired  ambulacrum  is  situated  in  the  deep  anterior  sulcus. 

The  apical  system  is  much  elongated,  mdely  separating  the  ambulacral  areas. 

The  peristome  is  situated  anteriorly  and  is  transversely  oval. 

Related  form^. — This  species  is  most  closely  related  to  Cardiaster  cinctus  hut  is  smaller  and 
has  a  somewhat  less  pronounced  anterior  sulcus  and  a  more  inflated  test. 

Locality. — Two  and  a  half  miles  northwest  of  Matawan,  N.  J. 

Geologic  horizon. — AlerchantviUe  clay  of  Matawan  group,  Upper  Cretaceous. 

Collection. — Geological  Survey  of  New  Jersey. 

Cardiaster  curtus  Clark,  n.  sp. 
Plate  XXXVII,  figures  la-h. 

Determinative  characters. — Test  small,  cordate,  high  anteriorly,  clearly  marked  anterior 
groove  with  well-defined  keel  on  either  side;  ambulacra  wide,  interambulacra  with  large  plates; 
peristome  near  posterior  margin. 

Dimensions. — Length  22  millimeters;  width  19  millimeters;  height  12  millimeters. 

Description. — The  two  specimens  of  tliis  small  species  are  fragmentary  although  retaining 
the  most  important  characteristic  portions. 

The  test  is  cordate,  elevated  toward  the  posterior  margin  and  with  broad  and  deep  anterior 
groove.  The  ambulacra  are  broad,  the  poriferous  zones  are  clearly  marked  on  the  upper  sur- 
face. The  pore  pairs  are  oval  above  and  more  nearly  roimd  toward  the  ambitus.  The  surface 
of  the  plates  is  covered  by  minute  granules. 

The  interambulacra  are  composed  of  large  plates  covered  with  minute  granules. 

The  apical  system  is  elongate,  the  four  genitals  varying  in  shape  and  size.  The  two  antero- 
lateral oculars  are  very  large  and  separate  the  antero-lateral  from  the  postero-lateral  genitals 
which  are  in  contact,  the  latter  isolating  the  two  postero-lateral  oculars  from  the  remainder  of  the 
apical  system. 


CEETACEOUS   ECHINODEEMATA.  85 

The  peristome  is  near  the  posterior  margin.     The  periproct  is  not  preserved. 
Locality. — Twenty-five  miles  southwest  of  Mingusville  (now  Wibaux),  Mont. 
Geologic  Jiorizon. — Fox  Hills  ( ?)  sandstone  of  Montana  group,  Upper  Cretaceous. 
Collection.— U .  S.  National  Museum  (31201). 

Genus  HOLASTER  Agassiz. 

HoLASTER  SIMPLEX  Shumard. 

Plate  XXXIV,  figures  3a-b;  Plate  XXXVIII,  figures  la-j;  Plate  XXXIX,  figures  lar-g. 

Eolasler  simplex  Shumard,  1853,  Pal.  Expl.  Red  River  of  Louisiana  in  1852,  p.  210,  PI.  Ill,  fig.  2. 

Uolastcr  comanchesi  Marcou,  1858,  Geology  of  North  America,  p.  40,  PJ.  Ill,  fig.  3. 

Holaster  simplex  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  450. 

Holaster  comanchesi  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  449. 

Holaster  simplex  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 

Eolasler  comanchesi  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 

Holaster  simplex  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  3. 

Holaster  comanchesi  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  3. 

Holaster  simplex  Clark,  1891,  Johns  Hopkins  Univ.  Oirc,  vol.  10,  No.  87,  p.  77. 

Holaster  simplex  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Holaster  simplex  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  76-78,  Pis.  XXVIII,  figs,  la-g;  PI.  XXXIX,  figs.  la-d. 

Holaster  computus  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  pp.  155,  156,  PL  XXIV,  fig.  10;  PL  XXV, 

fig.  14;  PL  XXVI,  figs.  6-8. 
Holaster  nanus  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  156,  PL  XXIV,  fig.  14;  PL  XXVI,  fig.  11. 
Holaster  simplex  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  157,  PL  XXV,  fig.  13. 
Holaster  supernus  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  pp.  157,  158. 
Holaster  completus  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  5,  pp.  45,  47. 
Holaster  nanus  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  5,  pp.  45,  47. 

Determinative  characters. — Test  oblong,  cordiform;  upper  surface  much  elevated,  roimded, 
and  grooved  on  the  anterior  face;  lower  surface  flat;  apex  nearly  central.  Ambulacra  wide; 
pores  unigeminal,  with  slitlike  openings  in  the  upper  portion  of  the  column  that  become  indis- 
tinct toward  the  margin  and  upon  the  base.  Apical  system  compact  and  not  greatly  elongated. 
Peristome  transversely  oval,  situated  near  the  anterior  margin.  Periproct  large,  on  truncated 
posterior  margin. 

Dimensions. — Length  32  to  70  milUmeters;  width  30  to  60  milUmeters;  height  14  to  53 
millimeters. 

Description. — The  test  is  oblong,  cordiform,  much  elevated,  rounded  above  and  flattened 
below.  A  shallow  groove  occupies  the  anterior  face  of  the  test,  producing  a  feeble  emargination 
of  the  anterior  ambitus.  A  slight  ridge  extends  along  the  Une  of  the  central  suture  of  the  single 
interambulacrmn,  which  is  suddenly  terminated  by  the  truncated  face  of  the  posterior  margin. 

The  ambulacra  are  wide.  The  poriferous  zones  of  the  paired  ambulacra  are  in  the  case 
of  the  posterior  pair  bent  more  or  less  forward  in  their  upper  portions,  and  in  the  case  of  the 
anterior  slightly  backward.  The  pores  of  the  paired  ambulacra  have  elongated  openings  in  the 
upper  portion  and  become  very  small  and  indistinct  below.  The  pores  of  the  unpaired  ambula- 
crum are  exceedingly  small. 

The  smf  ace  of  both  interambulacral  and  ambulacral  plates  are  covered  by  small  tubercles, 
between  which  are  nimierous  microscopic  granules. 

The  apical  system  is  compact  and  rather  short.  The  four  genital  plates  are  large  and 
broad.     The  two  interposed  oculars  are  large,  the  remaining  three  very  small. 

The  peristome  is  large,  transversely  oblong,  and  situated  near  the  anterior  margin.  The 
periproct  is  oval,  acuminate  above,  and  situated  on  the  truncated  posterior  border. 

The  variations  in  this  species  are  very  pronounced,  some  of  the  individuals  being  high  and 
globose  and  others  low  and  flat.  A  critical  examination  of  a  large  number  of  specimens  affords 
no  satisfactory  criteria  for  the  recognition  of  the  new  species  established  by  Marcou  and  Cragin. 

Related  forms. — H.  simplex  is  very  like  //.  Ixvis  var.  planus,  from  the  European  Cretaceous, 
but  is  more  elevated  and  distinctly  broader  posteriorly. 


86  MESOZOIC    AXD   CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

Localities. — Fort  Wasliita  (type),  Bexar  County  (figured  specimen  A),  near  Fort  Worth,  at 
Preston,  Grayson  County  (figured  specimen  B),  on  the  Red  Eiver,  near  Austin,  and  near  El  Paso, 
Tex. ;  near  Fort  Washita,  Okla. 

Geologic  horizon. — Washita  group  of  the  Comanche  series.  Cretaceous. 

Collections. — U.  S.  National  Museum  (8382 A);  Geological  Survey  of  Texas  (B);  Johns 
Hopkins  Univereity. 

Family  SPATANGID.E. 

Genus  ENALLASTER  D'Orbigny. 

Enallaster  texanus  (Roemer). 

Plate  XXXIX,  figures  2a-g. 

Toxaster  texanus  Roemer,  1849,  Texas,  p.  393. 

Toxaster  texanus  Roemer,  1852,  Die  Kreidebildungen  von  Texas,  pp.  85,  86,  PI.  X,  fig.  3. 

Toxaster  ungula  Giebel,  1853,  Naturwiss.  Ver.  in  Halle  Jahresb.,  p.  373. 

Enallaster  texanus  D'Orbigny,  1853-60,  Paleontologie  franfaise,  vol.  6,  p.  184,  PI.  DCCCL,  figs.  1-7. 

Toxaster  texanus  Conrad,  1857,  TJ.  S.  and  Mex.  Boundary  Survey  Rept.,  vol.  1,  pt.  2,  p.  145,  PI.  I,  figs.  2a-c. 
Enallaster  texanus  Desor,  1858,  Synopsis  des  ^chinides  fossiles,  p.  358. 

Toxaster  texanus  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 

Toxaster  texanus  Meek,  1S64,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  3. 

Enallaster  texanus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Enallaster  texanus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Enallaster  texanus  Clark,  U.  S.  Geol.  Survey  Bull.  97,  pp.  78,  79,  PL  XXXIX,  figs.  2a-g. 

Enallaster  inflatus  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  pp.  150,  151,  PL  XXIV,  fig.  13. 

Enallaster  texanus  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  151. 

Enallaster  texanus  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  5,  p.  41. 

Enallaster  inflatus  Cragin,  1894,  Colorado  Coll.  Studies,  vol.  5,  pp.  45,  47. 

Enallaster  texanus  Hill  and  Vaughan,  1898,  U.  S.  Geol.  Survey  Eighteenth  Ann.  Rept.,  pt.  2,  PL  LIII,  figs.  4a-b. 

Enallaster  texanus  Hill,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  7,  p.  226,  PL  XXVII,  figs.  4a-b. 

Enallaster  sp.  Hill,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  7,  p.  283. 

Determinative  characters. — Test  oblong,  cordiform,  broad  in  anterior  portion,  contracted 
and  truncated  posteriorly,  with  deep  anterior  groove;  upper  surface  convex,  elevated;  base  flat, 
depressed  at  the  peristome;  sides  rounded;  apex  excentric  and  posterior.  Ambulacra  narrow 
and  unequal,  the  posterolateral  pair  much  shorter  than  the  others.  Apical  system  small  and 
compact.     Periproct  situated  high  above  the  margin. 

Dimensions. — Length  16  to  45  millimeters;  -svidth  14  to  38  millimeters;  height  9  to  27 
millimeters. 

Description. — The  test  is  oblong,  cordiform,  and  elevated.  Tlie  upper  sm-face  is  convex, 
with  a  well-defined  anterior  groove,  narrow  and  slightly  depressed  at  its  head.  On  the  posterior 
face  the  surface  is  truncated  to  the  margin.  The  sides  are  rounded  and  inflated.  The  base  is 
flat,  except  for  the  peristonal  depression  near  the  anterior  margin  and  the  central  elevated  region 
extending  from  the  same  to  the  posterior  border. 

The  ambulacra  are  narrow  and  very  imequal.  The  antero-lateral  pair  are  large  and  curved 
backward  in  their  upper  portions.  The  pores  are  very  unequal;  those  of  the  anterior  zone  are 
smaU  and  near  together,  those  of  the  posterior  elongated,  the  outer  nearly  twice  as  large  as  the 
inner  series.  There  are  about  thirty-five  pairs  of  pores  in  the  petaloidal  portion  of  each  poriferous 
zone. 

The  postero-lateral  pair  are  short  and  quite  symmetrical  in  structure.  There  are  sixteen 
pairs  of  pores  in  the  petaloidal  portions  of  each  poriferous  zone. 

The  anterior  unpaired  ambulacrmn  is  situated  in  the  anterior  groove  and  is  wider  than  the 
other  areas.  An  elongated  pore  appears  in  the  external  rows  on  alternate  plates.  On  the  inter- 
vening plates  the  small  rows  are  closely  approximated.  In  the  lower  portion  of  each  column  the 
plates  are  large  and  oblong.     A  pair  of  minute  pores  occupies  the  lower  outer  corner  of  each. 

The  surface  of  the  test  is  covered  with  a  minute  granulation,  scattered  among  which  are 
numerous  small  tubercles. 


CEETACEOUS  ECHINODEEMATA.  87 

The  apical  system  is  small  and  compact,  and  the  four  large  genital  plates  are  distinctly  per- 
forated. The  right  anterolateral  plate  occupies  the  center  of  the  disk.  The  five  small  oculars 
are  wedged  in  between  the  genitals. 

The  peristome  is  transversely  oblong  and  situated  in  a  depression. 

Tlae  periproct  is  situated  lugh  upon  the  truncated  posterior  margin  and  is  small  and  oval, 
acuminate  below. 

Related  forms. — It  seems  not  improbable  that  Spatangus  columhianum,  described  by  Lea 
in  1840,  from  the  United  States  of  Colombia,  may  prove  to  be  identical,  or  at  least  very  closely 
related  to  the  Texan  form.  The  indistinct  figm-e  shows  a  different  arrangement  of  the  pores 
in  the  anterolateral  ambulacra,  but  it  is  doubtful  whether  it  can  be  depended  upon  for  such 
details  of  structure. 

Enallaster  peruvianus,  described  by  Gabb  in  1876,  from  material  obtained  from  Peru,  seems 
to  be  identical. 

Among  the  European  Enallasters  none  apparently  are  closely  related  to  Enallaster  texanus. 

Localities. — Very  common  near  Fredericksbm-g  (type),  Leon  Springs  (figured  specimen),  and 
at  numerous  other  localities  in  Texas,  and  near  Inichtea,  N.  Mex. 

Geologic  horizon. — ^Trinity,  Fredericksburg,  and  Washita  groups  of  the  Comanche  series, 
Cretaceous. 

Collection. — U.  S.  National  Museum  (98.57). 

Enallaster  obliquatus  Clark. 
Plate  XL,  figures  la-1. 

.Enallaster  obliquatus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Enallaster  obliquatus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  79,  80,  PL  XL,  figs.  la-1. 

Determinative  cJiaracters. — ^Test  oval,  cordiform;  upper  surface  convex,  flattened  and 
depressed  anteriorly,  elevated  posteriorly;  lower  sm-face  flat,  with  peristomial  depression;  apex 
forward  of  the  center.  Ambulacra  narrow,  unequal.  Surface  of  the  plates  covered  with  small 
tubercles  and  intervening  microscopic  granulation.  Ajaical  system  compact.  Peristome  trans- 
versely subpentagonal.     Periproct  situated  on  truncated  posterior  margin. 

Dimensions. — Length  49  miUimeters;  width  45  miUimeters;  height  26.5  millimeters. 

Description. — This  species  has  a  broad  cordiform  test,  flattened  and  slanting  on  the  anterior 
upper  surface,  whence  the  name  obliquatus.  The  anterior  groove  is  deep,  wider  at  its  head,  and 
cuts  broadly  into  the  anterior  margin.  The  posterior  portion  of  the  test  is  elevated  near  the 
apex  and  obliquely  truncated  toward  the  margin.  The  sides  are  sloping  anteriorly,  fuller  pos- 
teriorly.    The  base  is  flat  with  a  deep  pei'istomial  depression. 

The  ambulacra  are  narrow  and  unequal.  The  anterolateral  pair  are  slightly  depressed 
and  curved  backward  in  the  upper  portion.  The  pores  are  unequal,  those  of  the  anterior  zone 
smaU  and  near  together,  those  of  the  posterior  elongated,  the  outer  much  more  so  than  the  inner 
series.     There  are  about  40  pairs  of  pores  in  each  zone. 

The  posterolateral  pair  are  short  and  slightly  depressed.  The  pores  are  more  nearly  equal 
and  about  24  pairs  are  found  in  each  zone.  The  single  ambulacrum  is  placed  in  the  anterior 
groove  and  is  much  wider  than  the  paired  ambulacra.  The  pores  of  the  dift'erent  plates  vary  in 
size  and  position.     The  plates  in  the  lower  portions  of  the  areas  are  large  and  oblong  in  form. 

The  surface  of  the  test  is  covered  with  minute  tubercles  between  wliich  is  a  microscopic 
granulation.     The  apical  system  is  smaU  and  compact. 

The  peristome  is  transversely  subpentagonal.  The  periproct  is  oval  and  situated  high  on 
the  truncated  posterior  margin. 

Belated  forms. — E.  obliquatus  is  separated  from  E.  texanus,  the  only  other  representative 
of  this  genus  from  the  Cretaceous  deposits  of  the  United  States,  by  its  broader  depi'essed  form, 
more  sunken  anterior  sulcus,  and  lower  position  of  the  periproct.  These  features  seem  to  be 
characteristic  of  nearly  all  the  forms  from  the  Glen  Rose  beds  and  perhaps  should  not  be  re- 
garded as  of  specific  value.     Some  specimens  more  or  less  intermediate  in  their  characters  are 


88  MESOZOIC    AXD   CENOZOIC    ECHINODERMATA   OF    THE    UNITED    STATES. 

found,  and  it  may  perhaps  be  wiser  to  regard  the  difference  as  varietal  rather  than  specific.  This 
species  is  related  to  E.  mexicanus,  described  by  Cotteau  in  1890,  from  material  obtained  from 
Mexico. 

Localities. — Near  Austin  (type)  and  Glen  Rose  and  other  localities  in  Texas. 

Geologic  horizon. — Glen  Rose  limestone  of  the  Trinity  group,  Comanche  series,  Cretaceous. 

Collections. — U.  S.  National  Museum  (12237);  Geological  Survey  of  Texas. 

Genus  HEMIASTEK.  Desor. 

Hemiaster  elegans  Shmnard. 

Plate  XLI,  figures  la-c;  Plate  XLII,  figures  la-h;  Plate  XLIII,  figures  la-f. 

Hemiaster  elegans  Shumard,  1853,  Pal.  Expl.  Red  River  of  Louisiana  in  1852,  p.  210,  PL  II,  figs.  4a-c. 

Toxaster  elegans  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 

Toxaster  elegans  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177)  p.  3. 

Macraster  texanus  Roemer,  1888,  Neues  Jalirb.,  vol.  1,  pp.  191-195,  PI.  VI,  figs.  1^. 

Epiaster  elegans  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Epiaster  elegans  Clark,  1893,  Johns  Hopkins  Univ.  Circ. ,  vol.  12,  No.  103,  p.  52. 

Epiaster  elegans  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  80-82,  PI.  XLI,  figs,  la-b;  PI.  XLII,  figs,  la-b;  Pi.  XLIII, 

figs.  la-e. 
Epiaster  electus  Cragin,  1893,  Geol.  Survey  Texas  Fotu-th  Ann.  Rept.,  p.  152. 
Epiaster  elegans  Cragin,  1893,  Geol.  Stu^ey  Texas  Fourth  Ann.  Rept.,  p.  152. 

Epiaster  elegans  var.  nov.  prsenumtius  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  152. 
Epiaster  elegans,  Hill  and  Vaughan,  1898,  U.  S.  Geol.  Siu-vey  Eighteenth  Ann.  Rept.,  pt.  2,  PI.  LVI,  fig.  3. 
Epiaster  ehgans  mu,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  7,  pp.  226,  251,  260,  PI.  XXXVI,  fig.  4. 

Determinative  characters. — Test  large,  oblong,  cordiform,  flattened  both  above  and  below; 
sides  rounded,  with  a  shallow  anterior  groove  and  truncated  posterior  margin.  Ambulacra 
subpetaloidal,  depressed;  poriferous  zones  straight,  pores  with  elongated,  slitUke  openings. 
Apical  system  small.  Peristome  transversely  oval,  situated  near  the  anterior  margin.  Peri- 
proct  oval,  situated  on  the  truncated  posterior  margin. 

Dimensions. — Length  30  to  110  millimeters;  width  25  to  100  millimeters;  height  15  to  55 
millimeters. 

Description. — Roemer  in  1888  estabUshed  a  new  genus  and  species,  Macrdster  texanus,  for  a 
form  that  is  identical  with  Hemiaster  elegans  described  by  Shumard  in  1853.  There  does  not 
seem  to  be  a  sufficiently  wide  difference  between  the  characters  assigned  to  Macraster  and  those 
properly  belonging  to  Henaiaster  to  warrant  the  acceptance  of  the  former  genus  for  the  present 
species. 

The  test  is  very  large  and  flattened  on  both  the  upper  and  lower  surfaces.  The  sides  are 
round.  The  groove  on  the  anterior  face  is  shallow  and  cuts  the  margin  lightly.  The  posterior 
face  is  obliquely  but  not  broadly  truncated. 

The  ambulacral  areas  are  nearly  equal,  depressed,  with  a  distinct  furrow  on  the  upper  sur- 
face. The  poriferous  zones  are  long,  wide,  and  straight,  and  the  pores  consist  of  slitlike  openings. 
The  zones  are  subpetaloidal  on  the  upper  surface,  reacliing  quite  to  the  upper  margin  of  the 
rounded  sides.  The  unpaired  ambidacrum  is  narrower  than  the  others;  the  pores  are  smaller 
and  more  closely  approximated. 

The  surface  of  both  areas  is  covered  with  minute  tubercles,  between  which  are  microscopic 
granules. 

The  apical  system  is  small,  compact,  and  consists  of  four  large  perforated  genital  plates  and 
five  small  oculars. 

The  peristome  is  transversely  oval  and  situated  near  the  anterior  margin. 

The  periproct  is  large,  oval,  and  situated  on  the  truncated  face  of  the  posterior  margm. 

This  and  the  succeedmg  species  are  now  referred  to  the  genus  Hemiaster,  as  better  material 
has  shown  that  peripetalous  fascioles  are  present  although  poorly  developed  and  commonly 
destroyed  on  most  specimens. 

Related  forms. — H.  elegans  is  most  nearly  related  to  H.  whitei,  but  is  separated  from  it  by  its 
great  size,  its  excessively  long  subpetaloidal  areas,  and  the  position  of  its  periproct,  which  is  on 


CEETACEOUS   ECHIlSrODEEMATA.  89 

an  obliquely  truncated  surface  that  opens  downward  instead  of  being,  as  in  E.  whitei,  on  a  verti- 
cal face  that  opens  upward. 

Localities. — ^Fort  Wasliita  (type),  Fort  Worth  (figured  specimen),  and  numerous  other  locali- 
ties in  Texas. 

Geologic  horizon. — ^Fort  Worth  limestone  of  Washita  group,  Comanche  series,  Cretaceous. 

Collections. — U.  S.  National  Museum  (21887);  Johns  Hopkins  University;  Boston  Society 
of  Natural  Histoiy;  Geological  Survey  of  Texas. 

Hemiaster  whitei  Clark. 

Plate  XLIII,  figures  2a-c;  Plate  XLIV,  figures  la-h;  Plate  XLV,  figures  la-d,  2a-f. 

Toxaster  elegans  Conrad,  1857,  U.  S.  and  Mex.  Boundary  Survey  Kept.,  vol.  1,  pt.  2,  p.  146,  PL  XXI,  figs,  la-e.' 

Epiaster  whitei  Clark,  1S91,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Epiaster  whitei  Clai-k,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Epiaster  whitei  C\3j^,  1893,  U.  S.  Geol.  Sun^ey  Bull.  97,  pp.  82,  83,  PI.  XLIII,  figs.  2a-d;  PI.  XLIV,  figs.  la-g. 

Epiaster  hemiasterinits  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Kept.,  p.  1.53. 

Epiaster  ivhitei  Crsigin,  1893,  GeoL  Survey  Texas  Fourth  Ann.  Kept.,  p.  154. 

Epiaster  hemiasterirms  Cragin,  1894,  Colorado  CoU.  Studies,  vol.  5,  pp.  45,  47. 

Epiaster  whitei  Hill,  1901,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Kept.,  pt.  7,  p.  226. 

Determinative  characters. — ^Test  small,  cordiform;  upper  surface  convex,  elevated;  lower 
surface  flat;  sides  inflated;  apex  forward  of  the  center.  Ambulacra  moderately  broad,  petaloi- 
dal,  pores  with  elongated  openings;  anterolateral  pair  bent  slightly  backward  in  upper  part. 
Apical  system  subcentral.  Peristome  transversely  oval.  Periproct  small,  oval,  situated  high 
on  posterior  border. 

Dimensions. — ^Length  10  to  50  millimeters;  mdth  8  to  45  millimeters;  height  16  to  30 
millimeters. 

Description. — ^The  test  is  small  and  cordiform.  The  upper  surface  is  distinctly  elevated,  the 
apex  occupying  a  point  anterior  to  the  center.  The  lower  surface  is  flat  with  the  exception  of  the 
peristomial  depression.  The  sides  are  inflated  with  a  well-marked  groove  at  the  center  of  the 
anterior  face  and  a  prominent  truncated  surface  on  the  posterior  margin. 

The  ambulacra  are  moderately  broad.  The  poriferous  zones  are  subpetaloidal  in  their 
upper  part,  but  this  feature  does  not  continue  to  the  margin.  The  pores  in  the  paired  ambulacra 
are  all  of  about  equal  size  and  equally  spaced.  In  the  unpaired  ambulacrum  they  are  smaller 
and  nearer  together.  The  anterolateral  pair  are  bent  slightly  backward  in  then-  upper  part. 
They  are  distinctly  larger  than  the  posterolaterals.  The  interambulacra  are  prominent  and  the 
surface  of  the  plates  covered  with  minute  tubercles  and  microscopic  granules.  The  apical  system 
is  small,  compact,  and  consists  of  four  large  perforated  genital  plates  and  five  oculars.  The 
peristome  is  transversely  subpentagonal  and  situated  near  the  anterior  margin.  The  periproct 
is  small,  oval,  and  situated  high  on  the  truncated  posterior  margin. 

Related  forms. — In  many  particulars  Hemiaster  whitei  is  to  be  closely  associated  with  H. 
elegans.  It  is,  however,  more  elevated,  its  ambulacral  furrows  are  shorter,  and  its  periproct  is 
differently  situated.     (See  p.  88.) 

Localities. — Duck  Creek,  near  Denison  (type),  and  numerous  other  localities  m  Texas. 

Geologic  horizon. — ^Fredericksburg  group  and  lower  part  of  Washita  group,  Comanche  series, 
Cretaceous. 

Collections. — ^U.  S.  National  Museum  (4544,  9732,  31202);  Johns  Hopkins  University. 

Hemiaster  bex4.ri  Clark,  n.  sp. 

Plate  XL VI,  figures  la-e. 

Determinative  characters. ^Test  small,  upper  surface  nearly  flat,  elevated,  lower  surface 
rounded;  sides  inflated;  apex  nearly  central,  posterolateral  ambulacra  veiy  short,  interam- 
bulacra prominent.  Peristome  small,  only  slightly  depressed,  near  anterior  margin.  Periproct 
small,  situated  high  on  truncated  surface  of  posterior  margm. 

'  Figured  under  the  name  HolastcT  elegant. 


90  MESOZOIC   AND   CENOZOIC   ECHINODEKMATA   OF    THE    UNITED   STATES. 

Dimensions. — ^Length  22.5  millimeters;  width  21.25  millimeters;  height  15.5  millimeters. 

Desctnption.— This  small  species  has  a  broad,  nearly  fiat  upper  surface,  rising  toward  the 
center,  which  is  slightly  elevated.  The  lower  surface  is  rounded,  sloping  from  near  the  center  in 
all  du-ections.     The  sides  are  inflated.  , 

The  ambulacra  are  unequal,  tlie  posterolateral  pair  being  veiy  short.  The  poriferous  zones 
are  broad  and  shallow  and  but  little  depressed.  The  anterior  ambulacrum  is  broad  and  shallow. 
The  surface  is  covered  with  small  tubercles.     The  peripetalous  f asciole  is  distinct. 

The  peristome  is  small,  only  slightly  depressed,  and  near  the  anterior  margin.  The  peri- 
proct  is  small  and  situated  high  on  the  truncated  surface  of  the  posterior  margin. 

Locality. — ^Bexar  County,  Tex. 

Geologic  horizon. — Washita  group  of  the  Comanche  series,  Cretaceous. 

Collection. — ^U.  S.  National  Museum  (S330). 

Hemiaster  comanchei  Clark,  n.  sp. 
Plate  XL VI,  figures  2a-d. 

Determinative  characters. — Test  small  to  medium  size,  cordiform,  high,  lower  surface  flat, 
sides  inflated,  apex  forward  of  the  center,  peripetalous  fasciole  broad  and  clearly  marked ;  ambu- 
lacra rather  narrow,  depressed,  petaloidal,  the  posterolateral  considerably  shorter  than  the 
anterolateral,  apical  system  nearly  central;  peristome  near  forward  margin;  periproct  small, 
high  on  sloping  posterior  surface,  showing  clearly  from  above. 

Dimensions. — Length  25  to  60  millimeters;  width  22  to  50  millimeters;  height  18  to  30 
mUlimeters. 

Description. — The  test  of  this  species  is  small  to  medium  sized,  cordiform  in  ambital  outline 
and  high.  The  upper  surface  is  somewhat  inflated,  the  lower  surface  nearly  flat.  The  sides  are 
inflated.     The  apex  is  forward  of  the  center. 

The  ambulacra  are  rather  narrow  and  depressed,  the  poriferous  zones  petaloidal  but  narrow, 
the  posterolateral  pair  being  considerably  shorter  than  the  anterolateral.  The  single  anterior 
ambulacrum  in  a  broad,  moderately  depressed  sulcus.  The  interambulacra  are  covered  with 
numerous  irregularly  scattered  granules.  The  peripetalous  fascioles  are  broad  and  distinct,  with 
granules  scattered  here  and  there  over  the  surface.  The  apical  system  is  nearly  central  on  the 
upper  surface.  The  peristome  is  transversely  ovate  and  near  the  forward  margin.  The  periproct 
is  small,  high  on  sloping  posterior  surface,  and  showing  clearly  from  above. 

Related  forms. — H.  comanchei  is  the  earliest  of  the  Comanchean  hemiasters  and  possesses 
certain  generalized  features  which  suggest  that  it  is  the  ancestral  form  from  which  H.  whitei, 
H.  elegans,  H.  dalli,  and  H.  calvini  were  derived. 

Locality. — Santa  Monica  Springs,  bed  of  Colorado  River,  10  mUes  west  of  Austin,  Tex. 

Geologic  horizon. — Glen  Eose  limestone  of  Trinity  group,  Comanche  series.  Cretaceous. 

Collection. — Johns  Hopkins  University  (T  3012). 

Hemiastee  dalli  Clark, 

Plate  XLVII,  figures  la-f . 

Hemiaster  dalli  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Hemiaster  dalli  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Hemiaster  dalli  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  89,  PL  XLVIll,  figs.  2a-e. 

Determinative  characters. — Test  cordate,  subhexagonal,  depressed;  upper  surface  with 
sharp  ridges  between  the  ambulacral  furrows;  base  flat;  sides  rapidly  decUnuig;  anterior  margin 
deeply  grooved.  Ambulacra  unequal,  very  deeply  depressed  on  petaloidal  portions;  antero- 
lateral pair  much  bent  in  upper  part.  Peristome  oval,  situated  on  vertically  truncated  surface 
of  posterior  margin. 

Dimensions. — Length  45  millimeters ;  width  45  millimeters;  height  21  miUinieters. 


CRETACEOUS  ECHINODEEMATA.  91 

Description. — This  species  is  much  depressed,  M'ith  distinct  marginal  angles  that  give  it  a 
suhhexagonal  outline.  Prominent  ridges  cross  the  upper  surface  between  the  ambulacral  fur- 
rows. The  anterior  sulcus  cvits  deeply  into  the  test  and  grooves  the  anterior  margin.  The  sides 
decline  rapidly  to  the  flattened  base.  The  low  posterior  surface  has  a  nearly  vertical  tnmcation 
of  small  area. 

The  ambulacra  are  very  deeply  depresssd  on  the  upper  surface,  a  feature  much  more  pro- 
nounced than  in  any  other  American  species.  The  anterolateral  pair  are  bent  backward  in 
their  upper  part,  and  have  long,  deep  furrows.  The  posterolateral  pair  are  about  one-half  the 
length  of  the  anterior  pair.  The  single  ambulacrum  is  situated  in  the  broad,  deep,  anterior 
sulcus.  The  poriferous  zones  in  th<^  paiied  ambulacra  are  broad,  the  pores  oval,  those  of  each 
pair  united  by  a  shallow  furrow.  In  the  unpaired  ambulacrum  the  poriferous  zones  are  narrow, 
and  the  pores  small  and  approximated. 

The  surface  is  covered  with  small  tubercles  with  sunken  areolas  that  increase  in  size  toward 
the  base,  where  they  are  large,  with  distinctly  perforated  mamelons  and  crenulated  bosses.  A 
fine  microscopic  granulation  fiUs  the  interspaces. 

The  apical  system  is  sunken,  small,  and  posterior  to  the  center  of  the  upper  surface. 

The  peristome  is  transversely  oval  and  close  to  the  anterior  margin.  The  periproct  is  oval 
and  situated  on  the  truncated  surface  of  the  posterior  border. 

Related  forms. — The  very  deep  ambulacral  furrows  and  angular  outlme  readily  separate 
H.  dalli  from  any  other  American  species.     It  is  not  closely  allied  to  any  European  form. 

Locality. — Bexar  County,  Tex. 

Geologic  horizon. — Washita  group  of  the  Comanche  series,  Cretaceous. 

Collection. — U.  S.  National  Museum  (19114). 

Hemiaster  calvini  Clark. 

Plate  XLVII,  figures  2a-i. 

Hemiaster  calvini  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Hemiaster  calvini  Clark,  1S93,  U.S.  Geol.  Survey  Bull.  97,  pp.  30,  91,  PL  XLIX,  figs.  2a-i. 

Determinative  characters. — Test  oval,  cordate,  inflated;  upper  surface  elevated;  lower  sur- 
face flat;  posterior  margin  obliquely  truncated.  Ambulacra  moderately  depressed  on  the  upper 
surface.     Peristome  transversely  oval.     Periproct  oval,  high  on  truncated  posterior  border. 

Dimensions. — Length  21  to  38  millimeters;  width  20  to  35  millimeters;  height  16  to  33 
millimeters. 

Description. — This  species  has  an  elevated  test  that  is  oval,  cordate,  and  broadly  truncated 
on  the  posterior  margin.  The  anterior  sulcus  is  shallow  and  produces  but  a  feeble  groove  on  the 
anterior  margin.     The  base  is  flat. 

The  ambulacra  are  narrow.  The  poriferous  zones  are  broad;  the  petals  moderately 
depressed  and  of  good  length;  the  pores  in  the  petaloidal  portions  of  the  paired  ambulacra 
elongated,  slitlike,  those  of  the  unpaired  ambulacrum  small  and  approximated.  Beyond  the 
petals  the  pores  are  very  small,  and  occupy  the  lower  outside  corner  of  each  plate. 

The  surface  of  the  plates  is  covered  with  small  perforated  tubercles  rather  widely  scattered 
between  which  a  microscopic  granulation  intervenes.     The  peripetalous  fasciole  is  indistinct. 

The  apical  disk  is  small,  compact,  and  nearly  central. 

The  peristome  is  small,  transversely  oval,  and  situated  at  a  distance  from  the  margin.  The 
pariproct  is  oval  and  situated  high  on  the  tnmcated  surface  of  the  posterior  margm. 

Related  form.s. — H.  calvini  is  most  closely  related  to  H.  whitei,  from  which,  however,  it  is 
distinguished  by  its  more  elevated  form  and  its  small,  narrow,  anterior  sulcus.  The  apical 
system  is  also  more  excentric. 

Localities. — Shoal  Creek  (type),  near  Denison,  near  El  Paso,  and  other  localities  in  Texas. 

Geologic  horizon. — Washita  group  of  the  Comanche  series.  Cretaceous. 

Collections. — U.  S.  National  Museum  (12241);  University  of  Iowa. 


92  MESOZOIC   AND   CENOZOIC    ECHINODEEMATA   OF    THE    UNITED    STATES. 

Hemiaster  pakastatus  (Morton). 
Plate  XLVIII,  figures  la-n. 

Spatangus  sp.  Morton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.  17,  p.  286. 

Spatangus  cor-marinum  C!)  Morton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.  18,  p.  250,  PI.  Ill,  fig.  10. 

Spatangus  cor-marinum  (?)  Morton,  1830,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.,  vol.  6,  p.  199. 

Spatangus  parastatus  Morton,  1833,  Am.  Jour.  Sci.,  1st  ser.,  vol.  23,  p.  294. 

Spatangus  parastatus  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  77,  PI.  Ill,  fig.  21. 

Hemiaster  parastatus  Agassiz  and  Desor,  1847,  Catalogue  raisonne,  p.  141. 

Hemiaster  parastatus  D'Orbigny,  1847,  Prodrome,  vol.  2,  p.  270. 

Spatangus  parastatus  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  1160. 

Hemiaster  parastatus  D'Orbigny,  1853-1856,  Paleontologie  frangaise,  vol.  6,  p.  265,  PI.  DCCCXCIV,  fig.  4. 

Hemiaster  parastatus  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  373. 

Holaster  parastatus  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 

Hemiaster  (?)  parastatus  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7,  (177),  p.  3. 

Hemiaster  parastatus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  pi.  77. 

Hemiaster  parastatus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Hemiaster  parastatus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  83,  84,  PI.  XLV,  figs.  la-m. 

Hemiaster  parastatus  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Hemiaster  parastatus  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  298-300,  PI.  XV. 

Hemiaster  parastatus  Slocum,  1909,  Field  Mus.  Nat.  Hist.  Pub.  134,  Geol.  ser.,  vol.  4,  No.  1,  pp.  9,  10. 

Determinative  characters. — Test  cordiform,  inflated ;  upper  surface  elevated,  with  deep  groove 
on  anterior  surface  and  sharp  ridge  posteriorly  that  is  terminated  by  the  flat,  nearly  vertical, 
trimcated  face  of  the  posterior  margin.  Ambulacral  petals  depressed,  the  anterior  pair  twice  as 
long  as  the  posterior.  Apical  system  small,  compact.  Peristome  with  distinct,  overhanging 
lip.     Periproct  small,  situated  high  on  truncated  surface. 

Dimensions. — Length  37.5  millimeters;  width  37.5  millimeters;  height  28.12  miUimeters. 

Description. — This  interesting  and  rather  common  form  has  a  high,  cordiform  test,  with 
deep  anterior  sulcus  and  high  posterior  ridge  on  the  upper  surface,  the  latter  terminated  by  the 
high  and  nearly  vertically  truncated  face  of  the  posterior  margin.  The  sides  are  rounded  and 
inflated.     The  base  is  flat,  with  the  exception  of  the  peristomial  depression. 

The  ambulacra  are  very  unlike.  The  poriferous  zones  are  distinctly  petaloidal.  The  petals 
of  the  posterolateral  pair  are  short  and  broad.  Those  of  the  anterolateral  pair  are  bent  back- 
ward at  their  center,  depressed,  and  about  twice  the  length  of  the  posterolateral  pair.  The  pores 
are  slightly  elongated.  The  unpaired  ambulacrtim  is  very  broad,  the  poriferous  zones  far  apart, 
and  the  pores  small  and  approximated. 

The  surface  is  covered  with  small  tubercles,  between  which  are  numerous  microscopic 
granules. 

The  apical  system  is  small  and  situated  posteriorly  to  the  center  of  the  upper  surface.  The 
four  genital  plates  are  distinctly  perforated  and  separated  by  the  five  smaU  oculars. 

The  peristome  is  transversely  arched  and  bilabiate.  Tlie  lower  lip  projects  prominently. 
The  periproct  is  small  and  situated  high  on  the  truncated  surface  of  the  posterior  margin.  The 
peripetalous  fasciole  is  broad  and  distinct. 

Related  forms. — H.  parastatus  is  most  closely  related  to  H.  ungula,  from  which,  however,  it  is 
separated  by  its  deeper  and  broader  anterior  siflcus,  more  posterior  position  of  the  apical  system 
and  more  inflated  sides.  It  is  apparently  distinct  from  all  of  the  many  species  described  from 
European  deposits. 

Localities. — Gloucester  County  (type),  Timber  Creek,  and  Vincentown  (figtired  specimen), 
N.  J. ;  Pontotoc,  Ala.  (Slocum). 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group,  New  Jersey,  and  Ripley  formation, 
Alabama;  Upper  Cretaceous. 

Collections. — ^Academy  of  Natural  Sciences  of  Philadelphia  (1487);  American  Museum  of 
Natural  History,  New  York;  Johns  Hopkins  University. 


CRETACEOUS  ECHINODERMATA.  93 

HeMI ASTER  STELLA  (MortOll). 

Plate  XLVIII,  figures  2a-d. 

Spatangus  Stella  Morton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.18,  p.  245,  PI.  Ill,  fig.  11. 
Spataiigus  Stella  Morton,  1830,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.,  vol.  G,  p.  200. 
Spatangus  Stella  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  78,  PI.  Ill,  fig.  18.   ' 
Hemiaster  Stella  Agassiz  and  Desor,  1847,  Catalogue  raisonne,  p.  141. 
Hemiaster  Stella  Desor,  1858,  Synopsis  des  ^chinides  fossiles,  p.  373. 
Hemiaster  Stella  Gahh,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 
Hemiaster  (?)  Stella  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  3. 

Hemiaster  loetherhyi  De  Loriol,  1887,  Recueil  zool.  Suisse,  vol.  4,  pp.  391-394,  PI.  XVII,  figs.  5-8. 
Hemiaster  incrassatus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Hemiaster  Stella  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Hemiaster  stella  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  84,  85,  PI.  XLVI,  figs.  la-d. 
Hemiaster  Stella  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Hemiaster  stella  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  300-301,  PI.  XVI, 
figs.  1-4. 

Determinative  characters. — Test  small,  oval,  inflated,  rounded  before,  truncated  behind;  upper 
surface  elevated  posteriorly,  sloping  anteriorly;  anterior  groove  short,  not  reaching  the  ambitus. 
Ambulacra  straight,  depressed  above.  Apical  system  excentric  and  posterior.  Peristome 
bilabiate  and  near  the  anterior  border.  Periproct  small,  high  above  posterior  margin.  Fas- 
ciole  distinct. 

Dimensions. — Length  25  millimeters;  width  21.9  millimeters;  height  15.6  milhmeters. 

Description. — This  form  was  originally  described  by  Morton  in  1S30,  later,  in  1833,  it  was 
considered  by  the  same  writer  as  the  young  of  the  species  for  which  the  name  parastatus  was  then 
proposed.  H.  incrassatus  is  only  a  large  form  of  H.  stella  and  Hemiaster  wetherhyi  is  also  appar- 
ently identical  with  the  same  species. 

The  test  is  small,  oval,  and  cordate,  and  much  elevated  on  the  posterior  portion  of  the  upper 
surface.  The  whole  test  has  a  rounded,  full  outline,  that  is  much  increased  by  the  absence  of 
the  usually  deep  anterior  groove,  which  in  H.  stella  does  not  reach  the  margin.  The  posterior 
border  is  nearly  vertically  truncated. 

The  ambulacra  are  depressed  in  the  petaloidal  portions  which,  in  the  anterolateral  pair, 
are  twice  as  long  as  in  the  posterolateral.  The  poriferous  zones  are  narrow;  the  pores  have 
transverse  slitlike  openings.     The  unpaired  ambulacrum  is  situated  in  the  anterior  groove. 

The  surface  of  the  test  is  covered  with  innumerable  small  tubercles  between  which  is  a 
microscopic  granulation.  The  peripetalous  fasciole  is  very  distinct,  oval,  and  passes  with  a 
regular  curve  about  the  ends  of  the  petaloidal  areas.  The  surface  of  the  test  is  covered  with 
minute  tubercles,  between  which  are  microscopic  granules.  The  apical  system  is  small  and  is 
situated  posteriorly  to  the  center  of  the  upper  surface  of  the  test. 

The  peristome  is  transversely  oval,  bilabiate,  and  placed  near  the  anterior  margin.  The 
periproct  is  small,  oval,  and  is  situated  at  the  upper  part  of  the  truncated  posterior  margin. 

Belated  forms. — The  shallow  anterior  groove  which  falls  short  of  the  margin  and  the  fuU 
elevated  test  readily  distinguish  it  from  other  species. 

Localities. — Gloucester  (type),  near  Blackwoodstown  (figured  specimen),  and  Timber 
Creek,  N.  J. 

Geologic  horizon. — ^Vincentown  sand  of  Rancocas  group,  Upper  Cretaceous. 

Collections. — ^U.  S.  National  Museum  (2208);  Academy  of  Natural  Sciences  of  Philadelphia; 
Johns  Hopkins  University. 

Hemiastek  ungula  (Morton). 

Plate  XLVIII,  figures  3a-g. 

Spatangus  sp.  Morton,  1830,  Am.  Jour.  Sci.,  1st  ser.,  vol.  17,  p.  286. 
Spatangus  ungula  Morton,  1833,  Am.  Jour.  Sci.,  1st  ser.,  vol.  23,  p.  131,  PI.  X,  fig.  6. 
Spatangus  ungula  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  78.  PI.  X,  fig.  6. 
Micraster  ungula  Agassiz  and  Desor,  1847,  Catalogue  raisonne,  p.  141. 
Spatangus  ungula  Bronn,  1848,  Index  pateontologicus,  vol.  1,  p.  1161. 
39800°— 15 7 


94  MESOZOIC    AND   CENOZOIC   ECHINODERMATA   CF    THE    UNITED   STATES. 

Holastcr  imgula  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 
Ilcmiaster  ungula  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Hemiaster  ungula  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Eemimler  imgula  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  85,  86,  PI.  XLVI,  figs.  2a-g. 
Hemiaster  ungula  Johnson,  1905,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  57,  p.  7. 

Hemiaster  ungula  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  301-302,  PI.  XVI, 
figs.  5-11. 

Determinative  characters. — ^Test  oval,  cordiform,  elevated;  upper  surface  inflated,  elevated 
posteriorly;  lower  surface  flat;  sides  sloping;  anterior  sulcus  narrow  and  deep.  Ambulacra 
narrow;  poriferous  zones  straight,  depressed,  petaloidal.  Peripetalous  fasciole  deeply  bent 
inward  between  the  anterior  and  posterior  paired  ambulacra.  Apical  system  small,  compact. 
Peristome  transversely  oval  near  anterior  margin.     Periproct  oval,  supramarginal. 

Dimensions. — Length  31.25  millimeters;  width  28  millimeters;  height  21.9  millimeters. 

Description. — This  species  has  an  oval,  cordate  test,  that  is  very  much  elevated  in  the 
posterior  portion.  Anteriorly  the  upper  surface  slopes  rapidly,  so  that  the  margin  is  much 
thinned  down,  losing  the  full  round  aspect  of  the  previously  described  forms.  The  sharp  ridge 
on  the  posterior  portion  of  the  test  is  terminated  by  a  nearly  vertical  truncation  of  the  posterior 
margin.     The  base  is  flat,  save  for  the  peristomial  depression. 

The  ambulacra  are  narrow.  The  poriferous  zones  are  petaloidal,  straight,  and  deeply 
depressed  on  the  upper  surface.  The  unpaired  ambulacrum  is  placed  in  the  anterior  sulcus  and 
but  slightlj'  exceeds  the  other  areas  in  -width.  The  petals  of  the  anterolateral  pair  are  twice 
the  length  of  the  posterolateral.  The  pores  of  the  paired  ambulacra  are  elongated  and  sepa- 
rated, those  of  the  single  ambulacrum  small,  oval,  and  approximated. 

The  surface  of  the  test  is  covered  with  small  tubercles,  between  which  are  numerous  minute 
granules.  The  peripetalous  fasciole  is  distinct  and  bent  outward  between  the  anterior  and 
posterior  paired  ambulacra. 

The  apical  system  is  small  and  situated  posterior  to  the  center  of  the  upper  surface.  The 
right  anterolateral  genital  plate  is  very  large  and  widely  separates  the  posterior  pair  of  oculars. 
The  posterolateral  genitals  have  large  perforations. 

The  peristome  is  transversely  oval,  bilabiate,  with  a  prominently  projecting  lower  lip. 
The  periproct  is  large  and  is  situated  at  the  upper  part  of  the  truncated  face  of  the  posterior 
margin. 

Related  forms. — ^It  is  separated  from  H.  parastatus,  with  which  it  is  found,  by  the  narrower 
anterior  groove,  more  central  apical  system,  less  inflated  sides  and  sharper  posterior  keel. 

Localities.— ChesaTpeake  &  Delaware  Canal  (type),  and  Timber  Creek  and  Vincentown,  N.  J. 

Geologic  horizon. — ^Vincentown  sand  of  Eancocas  group,  Upper  Cretaceous. 

Collections. — Academy  of  Natural  Sciences  of  Philadelphia  (1503);  American  Museum  of 
Natural  History,  New  York;  Johns  Hopkins  University. 

Hemiaster  texanus  Roemer. 

Plate  XLIX,  figures  la-j. 

Hemiaster  texanus  Roemer,  1849,  Texas,  p.  393. 

Hemiaster  texanus  Roemer,  1852,  Die  Kreidebildungen  von  Texas,  p.  85,  PI.  X,  fig.  4. 

Hemiaster  americanus  Gabb,  1853,  Naturwiss.  Ver.  in  Halle  Jahresb.,  pp.  372,  373. 

Hemiaster  texanus  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 

Hemiaster  texanus  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  3. 

Hemiaster  texanus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Hemiaster  texanus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Hemiaster  texanus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  86,  87,  PI.  XLVII,  figs.  la^i. 

Hemiaster  texanus  Cragin,  1893,  Geol.  Survey  Texas  Fourth  Ann.  Rept.,  p.  155. 

Hemiaster  texanus  Aguilera,  1897,  Inst.  geol.  Mexico  Bol.  Nos.  4,  5,  6,  p.  215. 

Hemiaster  texanus  Hill  and  Vaughan,  1898,  U.  S.  Geol.  Survey  Eighteenth  Ann.  Rept.,  pt.  2,  PI.  LXI,  figs,  la,  lb. 

Hemiaster  ?  texanus  Bos^,  1899,  Inst.  geol.  Mexico  Bol.  No.  3,  p.  11. 

Hemiaster  texanus  Hill,  1902,  U.  S.  Geol.  Survey  Twenty-first  Ann.  Rept.,  pt.  7,  PI.  XLV,  fig.  5. 


CRETACEOUS   ECHINODERMATA.  95 

Determinative  characters. — Test  oval,  cordate,  declining  anteriorly,  elevated  slightly  posteri- 
orly; anterior  sulcus  broad  and  deep,  producing  groove  in  margin.  Ambulacra  broadly  de- 
pressed on  upper  surface;  antero-lateral  pair  bent  backward  in  upper  part;  unpaired  ambula- 
crum very  broad.  Apical  system  compact,  the  four  genitals  distinctly  perforated.  Peristome 
large,  transversely  oval,  bilabiate.  Periproct  large,  oval,  at  center  of  truncated  surface  of 
posterior  margin. 

Z>imens'io?is. -^Length  22  to  .38  millimeters;  ^vidth  21  to  36  millimeters;  height  15  to  20 
millimeters. 

Description. — This  important  species  is  broadly  cordate  and  slightly  depressed  on  the  upper 
surface ;  base  flat.  Posterior  to  the  apex  there  is  a  sharp  ridge  that  declines  gradually  toward  the 
obliquely  truncated  margin.     Anteriorly  the  upper  surface  declines  toward  the  anterior  border. 

The  ambulacra  are  broad,  very  unequal,  and  depressed  in  the  petaloidal  portions.  The 
poriferous  zones  are  broad,  the  pores  of  the  paired  ambulacra  elongated,  those  of  the  single  ambu- 
lacrum round  and  apj^roximated.  The  petals  of  the  anterolateral  pair  are  bent  backward  in 
their  upper  part  and  are  nearly  twice  the  width  of  the  posterolateral  pair.  The  single  ambula- 
crum is  very  broad,  the  poriferous  zones  widely  separated. 

The  surface  of  the  test  is  covered  with  small  tubercles  that  are  perforated  and  for  the  most 
part  crenulated.     A  microscopic  granulation  fills  the  intertubercular  space. 

The  apical  system  is  small  and  compact  and  situated  near  the  center.  The  four  genital 
plates  are  distinctly  perforated;  the  right  anterolateral  is  larger  than  the  others  and  serves  as 
the  madreporite.  The  five  oculars  are  wedged  between  the  genitals  and  are  deeply  cut  by  the 
upper  portions  of  the  ambulacra. 

The  peristome  is  large,  transversely  oval,  and  bilabiate.  The  periproct  is  large,  oval,  and 
situated  in  the  center  of  the  truncated  surface  of  the  posterior  margin. 

Related  forms. — Under  the  name  of  Hemiaster  americanus,  Giebel  pubhshed  in  1853  the 
description  of  a  new  species  of  Hemiaster  which  he  states  can  be  with  difficulty  distinguished 
from  H.  texanus.  It  is  considered  identical  in  the  present  report  since  the  differences  seem 
hardly  to  warrant  the  estabhshment  of  a  new  species.  Periaster  australis,  described  by  Gabb 
from  Peru,  as  far  as  the  figures  and  description  show,  must  be  a  Hemiaster,  and  to  all  appear- 
ances is  closely  allied  if  not  identical  ^vith  H.  texanus. 

Localities. — At  waterfall  of  Guadalupe  below  New  Braunfels  (type),  Fairview  (figured  speci- 
men), and  Austin,  Tex. 

Geologic  horizon. — Austin  chalk.  Upper  Cretaceous. 

Collections. — U.  S.  National  Museum;  Johns  Hopkins  University  (T  3013). 

Hemiaster  humpheeysanus  Meek  and  Hayden. 
Plate  XLIX,  figures  2a-f. 

Hemiaster  (?)  humphreysanus  Meek  and  Hayden,  1857,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  9,  pp.  147,  148. 

Hemiaster  (?)  humphreysanus  Gabb,  18.59,  <"at.  Invert.  Fossils  Cretaceous,  p.  19. 

Hemiaster  (?)  humphreysanus  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (177),  p.  3. 

Hemiaster  humphreysanus  Meek,  1876,  U.  S.  Geol.  and  Geog.  Survey  Terr.  Final  Rept.,  vol.  9,  pp.  5,  6,  PL  X,  figs.  la-g. 

Hemiaster  humphreysanus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Hemiaster  humphreysanus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 

Hemiaster  humphreysanus  Clark,  U.  S."  Geol.  Survey  Bull.  97,  p.  88,  PI.  XLVIII,  figs,  lar-f. 

Determinative  characters. — Test  oval,  cordate;  upper  surface  high,  flat,  with  broad,  vertical 
truncation  on  posterior  margin,  and  long  anterior  groove;  base  flat;  sides  rounded.  Ambulacra 
in  deep  furrows  that  reach  to  the  edge  of  the  elevated  sides.  Apical  system  large  and  compact, 
posteriorly  situated.  Peristome  small,  transversely  oval,  and  bilabiate.  Periproct  oval,  situ- 
ated high  on  posterior  margin. 

Dimensions. — Length  32.5  millimeters;  width  31.5  millimeters;  height  20.5  millimeters. 

Description. — The  absence  of  distinct  fascioles  on  the  type  specimens  of  this  species  caused 
Meek  and  Hayden  to  place  it  doubtfully  in  the  genus  Hemiaster,  to  which  beyond  doubt  it  belongs. 
The  test  is  fuU,  the  sides  rounded,  and  the  high  upper  surface  distinctly  flattened.     The  base  is 


96  MESOZOIC    AND   CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

also  flat,  vrith  the  exception  of  the  peristomial  depression.  The  situation  of  the  apex  so  far  pos- 
terior to  the  center  of  the  upper  surface  produces  a  long  anterior  sulcus,  that  grooves  the  anterior 
margin.     A  high,  vertically  truncated  surface  terminates  the  posterior  margin. 

The  ambulacra  are  broad,  very  unequal,  and  deeply  depressed  on  the  upper  surface.  The 
petals  of  the  posterolateral  pair  are  very  short,  those  of  the  anterolateral  very  long,  the  latter 
quite  three  times  the  length  of  the  former.  The  unpaired  ambulacrum  occupies  the  long  anterior 
sulcus.  The  anterolateral  pair  are  bent  backward  in  the  upper  part  and  forward  in  the  lower. 
The  poriferous  zones  are  broad,  the  pores  distinct  and  oval.  Since  much  of  the  surface  of  the 
test  has  sufi'erecl  removal  the  character  of  the  tubercles  and  granules  can  not  be  fully  determined. 

The  apical  system,  which  in  the  specimen  examined  has  been  largely  destroyed,  was  evi- 
dently large,  compact,  and  situated  far  posterior  to  the  center  of  the  upper  surface. 

The  peristome  is  small  and  situated  near  the  anterior  margin.  The  periproct  is  oval  and 
situated  on  the  vertically  truncated  surface  of  the  posterior  margin. 

Related  forms. — H.  Jiumphreysaniis  is  a  unique  form  and  is  not  related  to  any  species  of 
Hemiaster  hitherto  described. 

Locality. — One  hundred  and  fifty  miles  from  the  mouth  of  tlie  Yellowstone  River  in  Mon- 
tana (Meek  and  Hayden). 

Geologic  horizon. — Pierre  shale,  of  Montana  group.  Upper  Cretaceous. 

Collection.— U .  S.  National  Museum  (.331). 

Hemiaster  californicus  Clark. 

Plate  L,  figures  la-d. 

Hemiaster  californicus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Hemiaster  californicus  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Hemiaster  californicus  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  p.  90,  PI.  XLIX,  figs.  la-c. 

Determinative  characters. — Test  small,  subquadrate,  depressed;  upper  surface  flat,  with 
shallow  anterior  sidcus,  sloping  sides,  and  low  truncated  posterior  margin;  lower  surface  flat. 
Ambulacra  depressed,  in  shallow  furrows.  Apical  system  small,  postei'ior  to  center.  Peristome 
transversely  oval  near  anterior  margin.  Periproct  situated  on  the  low  truncated  surface  of  the 
posterior  margin. 

Dimensions. — Length  28  mUlimeters;  width  27  millimeters;  height  11  mdlimeters. 

Description. — This  form  has  the  details  of  its  structure  poorly  preserved  in  the  specimens 
examined,  although  it  belongs,  beyond  much  doubt,  to  the  genus  Hemiaster.  The  test  is  small, 
much  depressed,  and  subquadrate  in  ambital  outline.  It  is  broader  anteriorly,  Mith  a  feeble 
groove  in  the  center  of  the  anterior  margin.  The  posterior  portion  of  the  test  is  but  sHghtly 
more  elevated  than  the  anterior,  and  the  truncated  margin  is  low  and  narrow.  The  base  is  flat, 
with  the  exception  of  the  peristomial  depression. 

The  ambulacra  are  but  slightly  depressed  in  the  petaloidal  portions.  The  poriferous  zones 
are  broad,  and  the  oval  pores  are  united  by  shallow  furrows.  The  apical  system  is  smaU  and 
situated  shghtly  forward  of  the  center.  The  peristome  is  transversely  oval  and  situated  near 
the  anterior  margin.  The  periproct  is  small,  oval,  and  situated  on  the  low,  truncated  surface  of 
the  posterior  border. 

Related  forms. — From  its  shallow  ambulacral  furi-ows,  Hemiaster  californicus  may  be  com- 
pared to  H.  humphreysanus,  but  is  readily  separated  from  it  because  of  its  more  central  apical 
system  and  its  depressed  form. 

Locality. — Redding,  Shasta  County,  Cal. 

Geologic  horizon. — Chico  formation.  Upper  Cretaceous. 

Collection.— U.  S.  National  Museum  (31203). 

Hemiaster  beecheri  Clark,  n.  sp. 

Plate  L,  figures  2a-c. 

Determinative  characters. — Test  large,  cordiform,  elevated;  upper  surface  inflated,  depressed 
posteriorly;  ambulacra  broadly  depressed  on  dorsal  surface,  anterior  ambulacrum  in  broad 
sulcus. 


CRETACEOUS  ECHINODEKMATA.  97 

Dimensions. — Length  70  (?)  millimeters;  width  59  millimeters;  height  41  miUimetere. 

Description. — This  large  species  is  represented  by  a  single  specimen.  The  test  is  cordiform 
in  ambital  outline  and  elevated.  The  upjDer  surface  is  much  inflated,  sloping  rapidly  to  the  sides 
and  toward  the  posterior  margin,  which  is  much  depressed.  The  ambulacra  are  deeply  de- 
pressed, in  broad  grooves  which  distinctly  affect  the  ambital  outline.  The  interambulacra  form 
projcctmg  ridges,  the  posterior  interambulacrum  producing  a  sharp  crest.  The  apical  sj^stem 
is  situated  in  a  pronounced  apex  anteriorly.  The  peristome  is  located  in  a  well-marked  depres- 
sion near  the  anterior  margin. 

Localiti/. — Sage  Creek,  S.  Dak. 

Geologic  horizon. — Pierre  shale  of  Montana  group,  Uppc  r  Cretaceous. 

Collection. — Peabody  Museum,  Yale  University  (1863). 

Hemiaster  lacunosus  Slocum. 

Plate  L,  figures  3a-d;  Plate  LI,  figures  la-i. 

Eemiaster  lacunosus  Slocma,  1909,  Field  Mus.  Nat.  Hist.  Pub.  134,  Geol.  ser.,  vol.  4,  No.  1,  pp.  10,  11,  PI.  II,  figs.  1-7. 

Determinative  characters. — Test  small,  indistinctly  cordate,  upper  surface  slightly  convex, 
elevated  posteriorly;  sides  inflated;  lower  surface  nearly  flat.  Ambulacra  narrow,  poriferous 
zones  not  deeply  depressed  the  posterolateral  pair  being  quite  short.  Peripetalous  fasciole 
distinct.     Peristome  large,  near  anterior  margin.     Periproct  high  on  posterior  tnmcated  surface. 

Dimensions. — Length  17.8  to  2.3.4  mUlimeters;  width  16.3  to  23.6  millimeters;  height  11.8 
to  17  millimeters. 

Description. — Slocum  says: 

Test  small,  indistinctly  cordate,  ventral  surface  moderately  convex,  dorsal  surface  convex,  strongly  elevated  in  the 
posterior  interambulacral  area  and  gradually  sloping  with  an  indistinct  anterior  sulcus;  anterior  and  lateral  borders  in- 
flated, posterior  margin  truncated.  Ambulacral  areas  petaloid,  with  straight  petals  situated  in  depressions  of  the  surface, 
the  anterolateral  pair  nearly  twice  as  long  as  the  posterolateral  pair;  poriferous  zones  of  the  paired  petals  wide,  pores 
transversely  elongate  and  situated  far  apart.  Anterior  petal  longer  but  narrower  than  the  others  and  situated  in  a 
deep  depression  which  grades  into  an  indistinct  anterior  sulcus;  poriferous  zones  of  tliis  petal  narrow  and  far  apart; 
pores  small,  round,  and  separated  by  a  tubercle.  Interambulacral  areas  broad  and  composed  of  large  plates.  Surface 
of  the  test  covered  with  a  multitude  of  small  tubercles  with  sunken  areoles  that  increase  in  size  toward  the  peristome. 
The  tubercles  have  perforated  mamelons  and  crenulated  bosses,  the  interspaces  being  filled  with  microscopic  granula- 
tions. Peripetalous  fasciole  wide  and  distinct,  moderately  bent  inward  between  the  petaloid  areas  except  the  two 
posterior  ones.  Apical  disk  sunken,  small,  and  situated  somewhat  posterior  to  the  center  of  the  dorsal  surface,  the  four 
genital  plates  distinctly  perforated  and  separated  by  five  small  radial  plates.  Right  anterior  genital  plate  large,  convex 
and  forming  the  madreporite.  Peristome  transversely  arched,  bilabiate,  with  prominent  labrum.  Periproct  about 
the  size  of  the  peristome,  elongated  vertically  and  situated  near  the  top  of  the  posterior  truncation. 

Related  forms. — H.  lacunosus  resembles  H.  parastatus  in  general  form  and  proportions,  but  is  distinguished  from  that 
species  by  its  smaller  size  and  by  the  sunken  areoles  of  the  tubercles.  Moreover,  the  posterior  interambulacral  area  is 
rounded,  wliile  in  H.  parastatus  it  is  in  the  form  of  a  ridge.  H.  lacunosus  is  similar  to  H.  stella  in  size,  but  differs  from 
it  in  the  shape  of  the  fasciole,  the  sunken  areoles  and  the  form  of  the  anterior  margin.  It  resembles  H.  dalli  in  having 
sunken  areoles,  but  in  general  form  these  two  species  are  quite  dissimilar.  The  specific  name  adopted  refers  to  the 
sunken  areoles  by  wliich  the  species  is  distinguished. 

Locality. — Pontotoc  and  Houston,  Miss. 

Geologic  horizon. — Ripley  formation.  Upper  Cretaceous. 

Collections.— v.  S.  National  Museum  (31204);  Field  Museum  (P  10342). 

Hemiaster  kummeli  Clark. 

Plate  LII,  figures  la-c. 

Hemiaster  lummeli  Clark,  1907, in  Weller,  Cretaceous  paleontology   of   New  Jersey:   Geol.  Survey  New  Jersey,  pp 
303-304,  PI.  XVII,  figs.  1-3. 

Determinative  characters. — Test  cordate,  slightly  elevated.  Upper  surface  nearly  flat,  with 
wealdy  depressed  petaloidal  areas;  the  lower  surface  flat.  Peristome  with  distinct  overhano-ino- 
lip. 

Dimensions. — Length  30  to  55  millimeters;  width  30  to  40  millimeters;  height  about  20 
millimeters. 


98  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA   OF    THE    UNITED    STATES. 

Description. — This  species  is  represented  by  numerous  flattened  casts,  none  of  which  show 
clearly  the  original  form  of  the  test,  although  it  is  apparently  somewhat  flatter  than  the  other 
New  Jersey  Cretaceous  Hemiasters.  The  test  is  relatively  large.  It  is  but  slightly  elevated 
with  a  somewhat  flattened  upper  surface. 

The  ambulacra  are  pronounced,  with  weakly  depressed  petaloidal  areas.  The  unpaired, 
posterior  interambulacrum  is  nearly  flat  with  a  low  truncated  posterior  surface.  The  petals  of 
the  posterolateral  pair  are  relatively  long  and  narrow  and  less  than  twice  the  length  of  the 
anterolateral  pair.  The  unpaired  ambulacrum  is  not  deeply  depressed  and  does  not  form  a 
pronounced  sulcus  on  the  anterior  margm.  The  apical  system  is  small  but  not  as  strongly 
excentric  as  in  some  of  the  other  Cretaceous  species.  The  peristome  has  a  distinct  overhanging 
lip.     The  peripetalous  fascicles  can  not  be  seen. 

Related  forms. — This  species  is  related  to  both  H.  imrastatus  and  H.  welleri.  From  the 
former  it  is  separated  by  its  shallower  and  narrower  ambulacral  petals  and  less  elevated  form; 
from  the  latter  by  its  longer  and  narrower  posterolateral  ambulacral  petals  and  flatter  form. 

Locality. — LoriUard  clay  pits  near  Keyport,  N.  J. 

Geologic  horizon. — Woodbury  clay  of  Matawan  group,  Upper  Cretaceous. 

Collections. — Geological  Survey  of  New  Jersey;  Johns  Hopkins  University. 

Hemiaster  welleri  Clark. 
Plate  LII,  figures  2a-c. 

Hemiaster  welleri  Clark,  1907,  in  Weller,  Cretaceous  paleontology  of  New  Jersey:  Geol.  Survey  New  Jersey,  pp.  3(®- 
303,  PL  XVII,  figs.  4-6. 

Determinative  characters. — Test  cordifoma,  inflated;  upper  surface  only  slightly  elevated 
posteriorly;  lower  sm-face  flat;  sides  rounded.  Ambulacra  depressed.  Apical  system  smaU. 
Peristome  vnth  distinct  overhanging  Up.     Periproct  small,  high  on  posterior  truncated  surface. 

Dimensions. — Length  27  millimeters;  width  24  millimeters;  height  17  millimeters. 

Description. — ^This  species  has  afforded  few  specimens,  and  those  for  the  most  part  casts,  but 
it  is  evidently  distinct  from  the  other  forms  described.  The  test  is  moderately  high,  clearly  cor- 
dif orm,  and  with  depressed  ambulacra.  The  anterior  sulcus  is  broad  and  clearly  defined  but  does 
not  deeply  indent  the  anterior  ambitus.  The  posterior  ridge  is  not  greatly  accentuated  and  ter- 
minates in  a  well-defined,  trimcated  posterior  sm-face.  The  sides  are  rounded.  The  lower  sur- 
face is  slightly  inflated. 

The  ambulacra  are  moderately  depressed  in  their  petaloidal  portions,  the  posterolateral  pair 
being  considerably  shorter  than  the  anterolateral,  although  the  difference  is  less  marked  in  this 
species  than  in  the  other  New  Jersey  Cretaceous  Hemiasters.  The  anterior  ambulacrum  is  in  a 
broad  shallow  groove  that  largely  disappears  before  the  ambitus  is  reached. 

The  apical  system  is  small  and  imperfectly  shown  on  the  casts  from  which  its  characters  can 
be  alone  obtained. 

The  peristome  is  of  moderate  size  with  distinct  overhanging  lip.  The  periproct  is  small  and 
situated  high  on  the  truncated  posterior  surface. 

Related  forms. — Hemiaster  welleri  is  related  to  H.  parastatus  from  which,  however,  it  is  sepa- 
rated by  its  less  deeply  depressed  ambulacral  furrows  and  less  elevated  upper  surface.  It  also 
shows  points  of  resemblance  to  H.  Tcummeli  from  which,  however,  it  is  separated  by  its  lower 
posterolateral  ambulacral  petals  and  less  elevated  posterior  ridge  on  the  upper  sm-face. 

Localities. — Railroad  cut  1  mile  south  of  Lower  Jamesburg  (type) ;  3  miles  east  of  James- 
burg;  Reeves  clay  pit;  Lenola;  bluff  east  of  Atlantic  Highlands,  N.  J. 

Geologic  horizon. — ^Merchantville  clay  of  MataM'an  gi-oup  and  Navesink  marl  of  Moimiouth 
group,  Upper  Cretaceous. 

Collections. — Geological  Survey  of  New  Jersey;  Johns  Hopkins  Univei-sity. 


CRETACEOUS   ECHINODEKMATA.  99 

Genus  L.INTHIA  Merian. 

LiNTHIA    TUMIDULA    Claik. 

Plate  LIII,  figures  la-i. 

Linthia  tumidula  Clark,  1891,  Joluis  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Linthia  tumidula  Clark,  1893,  Johns  Hopkins  Univ.  Circ,  vol.  12,  No.  103,  p.  52. 
Linthia  tumidula  Clark,  1893,  U.  S.  Geol.  Survey  Bull.  97,  pp.  91,  92,  PI.  I,  figs.  la-i. 

Linthia  tumidula  Weller,  1907,  Cretaceous  paleontology  of  New  Jersey:   Geol.  Sur\'ey  New  Jersev,  pp.  304-305,  PI. 
XVIII,  figs.  1-9. 

Determirmtive  characters. — Test  oval,  cordifonn,  elevated;  apex  central;  posterior  border 
obliquely  truncated,  anterior  portion  grooved  by  narrow  sulcus;  sides  sloping.  Anibulacral 
furrows  long,  straight,  depressed;  poriferous  zones  broad,  pores  oval.  Apical  system  small, 
nearly  central.  Periproct  on  truncated  posterior  border.  Peripetalous  and  lateral  fascicles 
distinct. 

Dimensions. — Length  53  millimeters ;  width  50  miUimeters ;  height  28  milhmeters. 

Description. — This  .large  form  has  an  elevated  test,  with  flattened,  sloping  sides,  oval  outline, 
and  a  narrow,  moderately  depressed,  anterior  sulcus  that  grooves  the  anterior  margin.  The  base 
is  flat,  except  for  the  peristomial  depression. 

The  ambulacra  are  narrow  and  fm-row  for  a  long  distance  the  upper  surface  of  the  test  to  a 
moderate  depth.  The  poriferous  zones  are  broad  and  straight.  The  pores  are  large  and  oval, 
and  those  of  each  pau-  connected  by  a  shallow  fmTow.  The  anterolateral  jietals  reach  far  down 
the  sloping  sides  and  are  about  one  and  one-haK  times  as  long  as  the  posterolateral  pair. 

The  surface  of  the  test  is  covered  with  minute,  perforated  tubercles  that  are  much  longer  on 
the  base  than  on  the  upper  surface.  A  microscopic  granulation  fills  the  space  between  the  tuber- 
cles. Both  the  peripetalous  and  lateral  fascicles  can  be  readily  traced.  The  apical  system  is 
small,  nearly  central,  and  slightly  depressed.  The  peristome  is  transversely  oval  and  situated 
near  the  anterior  margin.  Tlie  periproct  is  small,  oval,  and  situated  but  a  short  distance  above 
the  posterior  margin. 

Localities. — Timber  Creek  and  Vincentown,  N.  J. 

Geologic  horizon. — Vincentown  sand  of  Rancocas  group.  Upper  Cretaceous. 

Collections. — American  Museum  of  Natural  History,  New  York;  Boston  Society  of  Natural 
History;  Johns  Hopkins  University. 

Linthia  variabilis  Slocum. 
Plate  LIV,  figures  la-1. 
Linthia  variabilis  Slocum,  1909,  Field  Mus.  Nat.  Hist.  Pub.  134,  Geol.  ser.,  vol.  4,  No.  1,  pp.  12-14,  PI.  Ill,  figs.  1-11. 

Determinative  characters. — Test  cordate,  upper  surface  elevated,  under  surface  nearly  flat, 
sides  inflated,  apex  nearly  central.  Ambulacra  in  relatively  deep  depressions.  Peristome  near 
anterior  margin.     Periproct  near  top  of  posterior  truncation. 

Dimensions. — Length  17.  1  to  31.6  millimeters;  width  16.0  to  29.1  millimetei-s;  height  10.1 
to  19.6  millimeters. 

Description. — Slocum  says : 

Test  distinctly  cordate,  truncated  posteriorly,  ventral  surface  depressed  convex,  dorsal  surface  elevated,  forming 
a  sharp  ridge  in  the  posterior  interambulacral  area.  Sides  inflated  and  eloping  to  the  lateral  and  anterior  margins; 
posteriortruncationslightly  concave  and  the  angle  between  the  truncation  and  the  base  line  varying  from  ,77°  to  90°. 
Ambulacral  areas  straight,  petaloid,  situated  in  comparatively  deep  depressions  of  the  dorsal  surf.ice.  Anterolateral 
pair  about  one  and  one-half  times  the  length  of  the  posterolateral  pair,  poriferous  zones  of  these  fom-  petals  wide,  pores 
elongated  and  slitlike.  Each  pair  of  pores  connected  by  a  shallow  groove  and  the  pore  near  the  border  of  the 
petal  the  larger.  Unpaii'ed  anterior  ambulacral  area  situated  in  a  deep  depression  the  continuance  of  which  forms  a 
sulcus  in  the  anterior  margin.  Poriferous  zones  of  this  area  narrow  and  situated  far  apart.  Pores  round  and  each  pair 
separated  by  a  tubercle.     Interambulacral  areas  broad  and  composed  of  large  plates.     Surface  of  the  test  covered  with 


100  MESOZOIC    AND   CENOZOIC    ECHINODEEMATA   OF    THE    UNITED    STATES. 

minute  perforated  tubercles  having  crenulated  bosses.  The  tubercles  increase  in  size  ds  they  approach  the  peristome. 
Interspaces  filled  with  small  tubercles  and  microscopic  granulations.  Both  peripetalous  and  lateral  fascioles  are  clearly- 
defined,  peripetalous  fasciole  decidedly  bent  inward  between  the  anterolateral  and  posterolateral  petals  and  somewhat 
less  so  between  the  other  petals.  Apical  system  situated  in  the  center  or  somewhat  anterior  to  the  center  of  the  dorsal 
surface,  small,  depressed,  having  the  four  genital  pl-ites  perforated  and  separated  by  five  small  radials.  Peristome 
transversely  elliptical,  situated  near  the  anterior  margin.  Labrum  prominent.  Periproct  somewhat  elongated  ver- 
tically and  situated  near  the  top  of  the  posterior  truncation. 

Related  forms. — L.  tumidula,  the  only  other  species  of  tliis  genus  hitherto  described  from 
the  ^Vmerican  Cretaceous,  is  so  unlike  L.  variabilis  that  detailed  comparison  is  imnecessary. 
Localities. — Onemile  Run,  Pontotoc,  and  Tippah  County,  Miss. 
Geologic  liorizon. — Ripley  formation,  Upper  Cretaceous. 
Collection. — Field  Museum,  Chicago  (P  10457). 


PART  II.— THE  CENOZOIC  ECHINODERMATA. 


By  William  Bullock  Clark  and  Mayville  W.  Twitchell. 


INTRODUCTION. 

GEOLOGIC   AND   GEOGRAPHIC   RANGE. 

The  Cenczoic  Echinodennat  a  discussed  in  tlie  succeeding  pages,  although  largely  confined  to 
the  Eocene,  are  by  no  means  absent  from  later  deposits.  The  Eocene  forms  are  very  abundant 
and  embrace  some  of  the  most  diagnostic  fossils  of  that  age,  but  they  are  less  common  than 
in  the  Cretaceous.  They  are  found  at  several  Eocene  horizons  on  the  Atlantic  and  Pacific  coasts, 
but  are  more  numerous  and  characteristic  in  the  Eocene  of  the  South  Atlantic  and  Gulf  Coastal 
Plain,  where  they  occur  in  large  numbers.  Nearly  all  that  have  been  collected  belong  to  the 
gi-oup  Echinoidea,  although  representatives  of  Crinoidea,  Asteroidea,  and  Holothuroidea  have 
been  found.  Among  the  echinoid  genera  recognized  are  Cidaris,  Coelopleurus,  Echinocyamus, 
Fibularia,  ScuteUa,  Mortonella,  Periarchus,  Clypeaster,  Echinanthus,  Cassidulus,  Breynella, 
Echinolampas,  Hemipatagus,  Brissopsis,  Linthia,  Schizaster,  Eupatagus,  Macropneustes,  and 
Sar  sella. 

The  Oligocene  strata  of  the  South  Atlantic  and  Gulf  areas  have  in  few  places  been  satisfac- 
torily delimited  from  the  Eocene,  so  that  the  age  of  some  of  the  echinoid  material  can  not  be 
determined  with  certainty.  Among  the  known  Oligocene  genera  of  the  South  Atlantic  and  Gulf 
areas  are  Cidaris,  Echinocyamus,  Laganum,  Amblj^^iygus,  Oligopygus,  Cassidulus,  Echinolampas, 
Agassizia,  Schizaster,  and  Eupatagus.  The  great  majority  of  the  foi-ms  come  from  Florida. 
The  Oligocene  deposits  of  California  have  also  furnished  specimens  of  Cidaris. 

The  Miocene  deposits  of  both  the  Atlantic  and  Pacific  coasts  have  afforded  a  considerable 
number  of  echinoderms,  chiefly  ecliinoids.    The  Atlantic  coast  Miocene  contains  Ophiodemia  ( ?) 
Cidaris,  Coelopleurus,  Psammechinus,  Scutella,  MeUita,  Encope,  Cassidulus,  Agassizia,  Brissus 
Plagionotus,  and  Echinocardium.     The  Pacific  coast  Miocene  has  furnished  Asterias,  Amphiura, 
Cidaris,  Scutella,  Dendraster,  Astrodapsis,  Scutaster,  Clj^ieaster,  and  Linthia. 

The  Pliocene  deposits  contain  very  few  echinodenns.  On  the  South  Atlantic  coast  from 
the  CaroUnas  southward  a  few  forms  have  been  recognized,  among  them  Strongylocentrotus 
Encope,  and  Diplothecanthus.  On  the  Pacific  coast  Dendraster,  Astrodapsis,  and  Schizaster  ( ?) 
are  found.  The  Miocene  and  Phocene  echinoids  of  the  Pacific  coast  have  been  found  to  be  of  more 
than  ordinary  value  in  the  determination  of  geologic  horizons.  This  is  due  to  their  limited 
geologic  range  and  to  the  fact  that,  where  present  at  all,  they  are  usually  abundant  and  well 
preserved. 

The  Pleistocene  deposits  likewise  have  furnished  very  few  echinoderms,  and  those  for  tlie 
most  part  of  species  living  in  the  adjacent  seas.  Among  those  recognized  from  the  Atlantic 
border  have  been  Asterias,  Strongylocentrotus,  MeUita,  Moira,  and  Toxopneustes.  On  the 
Pacific  coast,  on  the  other  hand,  several  species  of  Strongylocentrotus  and  Dendraster  are 
found. 

The  absence  of  species  identical  with  those  of  other  continents  and  particularly  of  Europe 
renders  it  impossible  to  attempt  detailed  correlation  of  American  and  foreign  horizons.  Genera 
represented  in  the  main  divisions  of  the  Cenozoic  in  America  are  with  scarcely  an  exception 
similar  to  those  typical  of  the  same  divisions  elsewhere. 

The  accompanying  tables  show  the  stratigi-aphic  jjosition  of  the  more  important  American 
Cenozoic  formations,  the  geologic  distribution  of  the  Cenozoic  Echinodermata  of  the  United 
States,  and  the  distribution  of  eastern  Gulf  Eocene  and  Oligocene  Echinodermata. 

101 


102 


MESOZOIC    AND   CENOZOIC   ECHINODERMATA   OF    THE    UNITED   STATES. 


Stratigraphic  position  of  the  more  important  American  Cenozoic/ormatio7is. 
[Vertical  parallel  liaes  indicate  formations  whicli  occur  in  separate  areas  and  wliose  exact  equivalence  is  not  established.] 


Series. 

Pacific  border 
(Calilomia). 

Eastern  Gulf  area.                        1             South  Atlantic  border. 

Middle  Atlantic  border. 

Pleistocene 

San  Pedro 

a  _  (Satilla 
0-°  lOkefenokee 

1  Pamlico 
Talbot 

Chowan 

Wicomico 

Sunderland 

:   Coharie 

PUocene? 

Lafayette  ? 

Lafayette? 

Lafayette 

■ 

PUocene 

Merced 
San  Diego 

Caloosahatchee  ||  Nashua 

Waccamaw 

Waccamaw 

Miocene 

San  Pablo 
Santa  Margarita 
Monterey 
Vaqueros 

Pascagoula 

Jacksonville  ||  Chootawhatchee 

DupUn 
Edistol  Marks  Head 

1 
1 

Yorktown 
St.  Marys 

Choptank  [|  Cohansey 
Calvert  |,  Kirk^vood 

Oligocene 

San  Lorenzo 

(Shoal  River 
^•^a  Alum  Bluff -^  Oak  Grove 
&oo{                     Ichipola 

Chattahoochee  |I  Tampa 

.  (Vicksburg 

Alum  Bluff 

[Chattahoochee 
Vicksburg 

Eocene 

Tejon 
Martinez 

m  '^  [jackson 

(Gosport 
Claibome{  Lisbon 

TaUahatta 
Hatehetigbee 

«Ucox    ^Tuscahoma 
Nanafalia 
Naheola 

Midway  .^Sucaniochee 
Clayton 

Jackson  [    Cooper 
Claibome{S-te«,, 

Wilcox  II  Williamsburg 

Midway  ||  Black  Mingo 

Castle  Hayn^ 

Trent 

g  ^  (Nanjemoy 
rt  "^  [Aquia 

Shark  River 

Geologic  distribution  of  the  Cenozoic  Echinodermata  of  the  United  States. 


Eocene. 

Oligo- 
cene. 

Miocene. 

Pliocene. 

Pleisto- 
ctn^ 

Crinoidea: 

Dicyclica — 
Flexibilia— 
Finnata— 

Antedoniae — 

Ste  Hero  idea: 
Asteroidea — 

Cryptozonia— 

Aster  iid8&— 

X 

X 

A-^terias  lincki  Miiller 

.  . 

X 

Ophiuroidea— 
Zygophiurse — 

0  ph  iodermat  id  ce — 

X 
X 

Amphiuridtc — 

1 

Echinoidea: 

Regularia  endobranchiata— 
Cidaroidea — 

Cidaridje— 

X 
X 
X 

X 
X 
X 
X 
X 
X 
X 
y 

Cidaris  moereus  de  Gregorio 

Cidaris  ordinatus  de  Gregorio 

Cidaris  blandis  de  Gregorio 

X 
X 
X 
X 




Cidaris  thouarsii  (?)  Valenciennes 

X 

INTRODUCTION. 

Geologic  distribution  of  the  Cenozoic  Echinodermata  of  the  United  States — Continued. 


103 


Eocene. 

Oligo- 
cene. 

Miocene. 

Pliocene. 

Pleisto- 
cene. 

Echinoidea— Continued. 

Regularia  ectobranchiata— 
Diademoidea— 
Arbacina— 

Arbaciidse — 

Coelopleums  infulatus  (Morton) 

X 

Coelopleums  aldriohi  Clark 

X 

Coelopleurus  improoerus  ( Conrad) 

X 
X 
X 

Coelopleums  sloani  Clark 

Diademina— 

Cyphosomatida^ — 

Orthcchinus  pretiosus  Clark 

X 

X 
X 

Echintna— 

Triplechinida? — 

Echinus  exerceus  de  Gregorio 

Echinus  ( ?)  sp 

Gagaria  amencana 

XX 

Psammeehinus  philanlhropus  (Conrad J 

X 
X 

Fsammechinus  exoletus  MeCrady 

Toxopneustes  v  irgiegatus  ( Lamarck) 

X 

Strongylocentrotida?— 

Stroncrvlocentrotus  drobachiensis  (Miiller) 

X 

Strongylocentrotus  franciscanus  A .  Agassiz 

X 
X 

Irregular  ia- 
Gnathostomata— 
Clypeastrina— 
Fibulariidae — 

Echinocyaraus  parvus  Emmons 

X 
X 
X 

Echinocvamiis  texanus  Twilchell 

Echinocvamus  vaughani  Twitchell 

X 

Sismondia  (?)  plana  Conrad 

X 

Sismondia  (?)  amoldi  Twitchell 

X 
X 

E?i 

Sismondia  (?)  coalingaensis  Twitchell 

Fibularia  meridionalis  (Meyer) 

X 
X 

Laganidje— 

Laganum  (?)  crustuloides  (Morton) 

X 
X 
X 
X 
X 

Laganum  aroherensis  Twitchell 1 

Laganum  Iloridanum  Twitchell 

ScutellidE^ 

X 
X 
X 
X 

Scutella  tuomey I  Twitchell 

Scutella  (?)  conradi  (Cotteau) 

Scutella  andersoni  Twitchell 

X 

X 
X 
X 
X 
X 

Scutella  ( ?)  merriami  (Anderson) 

Scutella  aberli  Conrad 

X 
X 
X 
X 
X 

Teriarchus  altus  Conrad 

1 

■'  ■  '1 

Feriarchus  protuberans  Twitchell 

1 

Dendraster  perrini  ( Weaver) 

X 
X 
X 
X 
X 

CO 
CO 

(?) 

Dendraster  gibbsli  (R^mond) 

Dendraster  coalingaensis  Twitchell 

(?) 

X 

Dendraster  excentricus  (Eschsciioltz) 

X 

Astrodapsis  antiselli  Conrad  

X 
X 
X 
X 
X 

Astrodapsis  whitneyi  Remond 

Astrodapsis  jacalitosensis  Arnold 

X 

X 

X 
X 

Encope  macrophora  Ravenel                        

X 

Cl3rpeastndie— 

Clypeaster  rogersi  (Morton)                                

X 

X 

X 
X 

Clypeastcr  (?)  brewerianus  (Redmond)     

Diplothecanlhus  dalli  Twitchell 

X 

(:) 

Echinanthus  georgiensis  Twitchell                

X 

Atelostomata— 
Astemata— 

Nucleolitida? — 

Amblypygus  merrilli  Twitchell                            .  .        

X 

X 
X 
X 

Oligopygus  lialdermani  (Conrad).          

- 

CassiduHdiT'^ — 

X 
X 
X 
X 

(?) 
(?) 

Cassidulus  (  Ulivnrluipvgus)  lyelli  (Conrad) 

Cas-^iiiuliis  ( Kli"\'iu'hop"ygus)  raveneli  Twitchell 

gj 

Cassidnlus  ( Uhvnchopvgus)  depressus  Twitchell 

I 

104 


MESOZOIC    AND   CENOZOIC   ECHINODERMATA    OF    THE    UNITED    STATES. 
Geologic  distribution  of  the  Cenozoic  Echinodermata  of  the  United  States — Continued. 


, 

Eocene. 

Oligo- 
cene. 

Miocene. 

Pliocene 

Pleisto- 
cene. 

Echinoidea — Continued. 
Irregularia— Contuiued. 

Atelostomata — Continued. 
.\stemata— Continued. 

Cassidulida^Continued. 

Cassidulus  ( l'ygorli>Tichus)  conradi  Conrad 

(!) 
X 
(?) 
CO 

CT 

Cassidiihis  ( PYgoriivnclius)  carolinensis  Twilchell 

Cassidulus  ( I'vgorlis-nciius)  georgiensis  Twitchell 

X 
X 
X 

Cassidulus  (Pvgorlivnchus)  gouldii  Bouve 

Cassidulus  ( PTgorhynchus)  alabamensis  Twitchell 

X 

Cassidulus  bem'i  Twitchell _ 

X 

Brevnella  gregorvi  Twitchell 

X 
X 

Echinolampas  aldrichi  Twitchell 

X 

Stemata— 

Spatangida^- 

xxxxx 

Hemipatagus  subrostratus  Clark 

Schizaster  armiger  Clark .     . 

X 
X 

Schizaster  americana  Clark 

^ 

Schizaster  atropos  ( Lamarck) 

X 

X 
X 

X 

Eupatagus  carolinensis  Clark 

X 

X 

Brissopsis  rimulatus  Ravenel 

X 
X 
X 
X 

Macropncustes  carolinensis  Clark 

Spatangus  (?)  pachecoensis  Pack 

X 

Agassizia  conradi  (Bouv^) 1 

X 
X 
X 
X 
X 
X 
X 

Echinocard ium  orthonotum  Conrad 

Echinocardium  got  hicus  ( Ravenel} 1 

Metfllia  rnvpnelianiit;  McCr';idy 

Metalia  holmesi  McCrady . . .  ^ i 

Holothurioidea: 

Paractinopoda— 

Synaptidse — 

Ctiiridotasp ..\     . 

X 
X 

Stratigraphic  distribution  of  eastern  Gulf  Eocene  and  Oligocene  Echinodermata. 


Eocene. 


Midway. 


Clai- 
borne. 


Oligocene. 


Vicks- 
burg. 


Apalachi- 
cola. 


Cidaris  blandis  de  Gregorio 

Cidaris  ordinatus  de  Gregorio. . 
Cidaris  perdubius  de  Gregorio. 
Cidaris  ma?reus  de  Gregorio. . . 
Cidaris  modcstus  de  Gregorio.. 

Cidaris  alabamensis  Morton 

Cidaris  sp 

Cidaris  mortoni  Conrad 

Cidaris  smithi  Clark 

Cidaris  georgiana  Clark . . : 

Coelopleurus  aldrichi  Clark 

Orthechinus  prctiosus  Clark. . . 

Gagaria  americana  Clark 

Echinus  exerceiis  de  Gregorio.. 
Echinus  sp . 


Echinocyamus  huxleyanus  Meyer. . . 

Echinocyamus  lexanus  Twitchell 

Echinocyamus  vaughani  Twitchell. . 

Fibularia  meridionalis  ( Meyer) 

Laganum  eldridgei  Twitchell 

Laganum  archerensis  Twitchell 

Laganum  Johnson i  Twitchell 

Laganum  floridanum  Tn-itcbell 

Laganum  dalli  Twitchell 

Sculella  mississippiensis  Twitchell... 

Mort  onella  quin^uefaria  (Say) 

Periarchus  lyelli  Conrad 

Periarchus  protuberans  Twitchell  ... 
Periarchus  pileus-sinensis  ^Ravenel), 

Clypeaster  rogersi  (Morton) 

Echinanthiis  georgiensis  Twitchell... 

Amblypygus  merrilli  Twitchell 

Oligopygus  wetherbyi  De  Loriol 

Oligopygus  haldermani  (Conrad) 


(.) 
X 
X 
X 
X 


X 

X 

(?) 

X 
X 


(?) 

X 


X 
X 
X 


INTRODUCTION. 
Stratigraphic  distribution  of  eastern  Gulf  Eocene  and  Oligocene  Echinodermafa — Continued. 


105 


Eocene. 

Oligocene. 

Midway. 

Wilcox. 

Clai- 
borne. 

Jackson. 

Vicks- 
burg. 

Apalachi- 
eola. 

Oligopygus  floridanus  Twitchell 

X 

•Cassidulus  (Rhj-nchopvfius)  Ivelli  (Conrad) 

X 
(■') 
(?) 
(?) 
(?) 
(?) 

Cassidulus  (Rh\Tichnpvgus)  patelliformis  Bouvi?.... 

(?) 
(?) 
(?) 
X 
X 
X 
X 

Cassidulus  (Rh\'nchopvsus)  depressus  Twitchell 

Cassidulus  ( ryf:orh\'no'hus)  conrad  i  Conrad 

Cassidulus  (Pvf^orli\'Tichus)  gcorgiensis  Twitchell 

Cassidulus  ( PvKorh™chus)  gouldii  Bouvc^ 

Cassidulus  ( Pygorhrachus)  alabamensis  Twitchell 

Echinolampas  aldrichi  Twitchell 

Hemipatagus  argutus  Clark 

X 

Agassizia  conrad  i  ( Bonv^) 

X 

Schizaster  armigcr  Clark 

X 

Schizaster  floridanus  Clark 

X 
X 

Schizaster  amcricana  Clark 

Linthia  alabamensis  Clark 

X 

Macropneustes  mortoni  ( Conrad ) 

X 

X 

X 

Eupatagus  floridanus  Clark 

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INTEODTJCTION.  IQY 

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1894. 

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Kennedy,  William,  Eocene  Tertiary  of  Texas  east  of  Brazos  River:  Acad.  Nat.  Sci.  Philadelphia  Proc,  pp.  113-115, 

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1896. 

Clark,  W.  B.,  The  Eocene  deposits  of  the  Middle  Atlantic  slope:  U.  S.  Geol.  Survey  Pull.  141,  167  pp.,  40  pis.,  1896. 

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1898. 

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39800°— 15 8 


110  MESOZOIC   AXD   CEIv^OZOIC    ECHIXODEEMATA    OF    THE    UNITED    STATES. 

1901. 

Clark,  W.  B.  and  Martin,  G.  C,  Systematic  paleontology,  Eocene;  ilollusca,  Brachiopoda,  and  Ecliinoderniata: 
Maryland  Geol.  Survey,  Eocene,  pp.  93-331,  Pis.  X-LXIV,  1901. 

1802.  ■' 

Arnold,  D.  and  A.,  Marine  Pliocene  and  Pleistocene  stratigraphy  of  the  coast  of  southern  California:  Jour.  Geology, 

vol.  10,  pp.  117-138,  Pis.  I-V,  1902. 
Clark,  H.  L.,  The  echinoderms  of  the  Woods  Hole  region  :  U.  S.  Fish  Comm.  Bull,  for  1902. 
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pp.  45-332,  Pis.  XI-XXXIX,  1902. 

1903. 

Arnold,  Ralph,  The  paleontology  and  stratigraphy  of  the  marine  Pliocene  and  Pleistocene  of  San  Pedro,  Cal.:  Califor- 
nia Acad.  Sci.  Mem.,  vol.  3,  1903. 

1904. 

Clark,  W.  B.,  Systematic  paleontology,  Miocene  Echinodermata:  Maryland  Geol.  Survey,  Miocene,  pp.  430-433, 
Pis.  CXIX,  CXX,  1904. 

1905. 

Anderson,  F.  M.,  A  stratigrapliic  study  in  the  Mount  Diablo  range  of  California:  California  Acad.  Sci.  Proc,  3d  ser., 

Geology,  vol.  2,  No.  2,  pp.  156-206,  with  plates,  1905. 
ScHUHERT,  C,  Catalogof  type  specimens  of  fossil  invertebrates  in  the  National  Museum:  U.  S.  Nat.  Mus.  Bull.  53,  pt.  1, 

704  pp.,  1905. 
Sears,  J.  H.,  The  physical  geography,  geology,  mineralogy,  and  paleontology  of  Essex  County,  Mass.,  418  pp.,  209  text 

figs.,  Salem,  1905. 

1906. 

Clark,  W.  B.,  and  others,  Characteristic  fossils  of  Maryland  formations:  Maryland  Geol.  Survey  Sixth  Kept.,  pt.  1,  pp. 
252-259,  Pis.  XVI-XXIII,  1906. 

1907. 

Arnold,  Ralph,  New  and  characteristic  species  of  fossil  mollusks  from  the  oil-bearing  Tertiary  formations  of  southern 

California:  i:.  S.  Nat.  Mus.  Proc,  vol.  32,  pp.  525-546,  Pis.  XXXVIII-LI,  1907. 
■ New  and  characteristic  species  of  fossil  mollusks  from  the  oil-bearing  Tertiary  formations  of  Santa  Barbara 

County,  Cal.:  Smithsonian  Misc.  Coll.,  vol.  1,  pt.  4,  pp.  419^47,  Pis.  L-LVIII,  1907. 
Arnold,  Ralph,  and  Anderson,  Robert,  Geology  and  oil  resources  of  the  Santa  Maria  oil  district,  Santa  Barbara 

County,  Cal.:  U.  S.  Geol.  Survey  Bull.  322,  161  pp.,  Pis.  XII-XXVI,  1907. 
Eldridge,  G.  H.,  and  Arnold,  Ralph,  The  Santa  Clara  Valley,  Puente  Hills,  and  Los  Angeles  oil  districts,  southern 

California:  U.  S.  Geol.  Survey  Bull.  309,  220  pp..  Pis.  XXV-XLI,  1907. 

1908. 

Arnold,  Ralph,  Fossils  from  Santa  Cruz  Mountains,  Cal.:  U.  S.  Nat.  Mus.  Proc,  vol.  34,  pp.  34.5-390,  Pis.  XXXI- 

XXXVII,  1908. 

New  brittle  star  from  Miocene  of  California:  U.  S.  Nat.  Mus.  Proc,  vol.  34,  pp.  403-406,  Pi.  XL,  1908. 

Weaver,  C.  E.,  New  ecliinoids  from  the  Tertiary  of  California:  Univ.  California  Dept.  Geology  Bull.,  vol.  5,  No.  17, 

pp.  271-274,  Pis.  XXI,  XXII,  1908. 

1909. 

Arnold,  Ralph,  Paleontology  of  the  Coalinga  district,  Fresno  and  Kings  counties,  Cal. :  V.  S.  Geol.  Survey  Bull.  396, 

101  pp.,  30  pis. 
Branner,  J.  C,  Newsom,  J.  F.,  and  Arnold,  R.,  V.  S.  Geol.  Survey  Geol.  Atlas,  Santa  Cruz  folio  (No.  163),  11  pp., 

2  pis.,  1909. 
Ball,  AV.  H.,  Contributions  to  the  Tertiary  paleontology  of  the  Pacific  coast — I,  The  Miocene  of  Astoria  and  Coos  Bay, 

Oregon:  U.  S.  Geol.  Survey  Prof.  Paper  59,  278  pp.,  23  pis.,  1909. 
Lambert,  J.,  Echinodermes:  Rev.  ci-it.  paleozoologie,  vol.  13,  1909,  p.  122. 
Pack,  R.  W.,  Notes  on  echinoids  from  the  Tertiary  of  California:  Univ.  California  Dept.  Geology  Bull.,  vol.  5,  No.  18, 

pp.  275-283,  pis.  23,  24,  1909. 
Weaver,  C  .  E  . ,  Stratigraphy  and  paleontology  of  the  San  Pablo  formation  in  middle  California :  Univ.  California  Dept. 

Geology  Pub.,  vol.  5,  No.  16,  pp.  243-269,  1909. 


INTRODUCTION.  Ill 

1910. 

Arnold,  Ralph,  and  Anderson,  Robert,  Geology  and  oil  resources  of  tlie  Coalinga  district,  Cal.:  U.  S.  Geol.  Survey- 
Bull.  398,  pp.  1-354,  Pis.  XXIir-LII,  1910. 

Clark,  W.  B.,  and  Twitchell,  M.  W.,  Geological  distribution  of  Mesozoic  and  Cenozoic  Echinodermata  of  the  United 
States:  Geol.  Soc.  America  Bull.,  vol.  20,  pp.  686-688,  1908. 

Grabau,  a.  W.,  and  Shimee,  H.  W.,  North  American  index  fossils,  invertebrates,  vol.  2,  909  pp.,  726  figs.,  1910. 

Lambert,  J.,  Echinodermes:  Rev.  crit.  paleozoologie,  vol.  11,  No.  1,  pp.  42-55,  1910. 

1911, 

Lambert,  J.,  Echinodermes:  Rev.  crit.  jjal^ozoologie,  vol.  15,  1911,  p.  64. 

Stbfanini,  G.,  Sugli  echini  terziari  dell'  America  del  Nord:  Soc.  geol.  italiana  Boll.,  vol.  30,  pp.  677-714,  PI.  XXII, 
Rome,  1911. 

Osservazioni  sulla  distribuzione  geografica,  sulla  origini  e  sulla  filogenesi  degli  Scutellidse:  Soc.  geol.  italiana 

Boll.,  vol.  30,  pp.  739-754,  1911. 

Note  echinologiche:  Revista  italiana  di  paleontologia,  vol.  17,  pt.  4,  pp.  1-16,  PI.  V,  1911. 


Note. — A  number  of  contributions  have  appeared  during  the  progress  of  this  report  tlirough  the  jjress,  the  results 

of  which  can  not  be  fully  incorporated  in  the  following  pages,  although  footnotes  concerning  some  of  them  have  been 

inserted.     Among  the  more  important  of  these  publications  are  : 

Pack,  R.  W.,  Notes  on  Scuiella  norrisi  and  Scuiaster  andersoni:  California  Univ.  Dept.  Geology  Bull.,  vol.  7,  No.  13, 
pp.  299-304,  PI.  XV,  1913.     Pack  furnishes  additional  information  of  value  regarding  the  species  mentioned. 

Kew,  W.  S.  W.,  Tertiary  echinoids  of  the  Carrizo  Creek  region  in  the  Colorado  Desert:  California  Univ.  Dept.  Geol- 
ogy Bull.,  vol.  8,  No.  5,  pp.  39-60,  Pis.  I-V,  1914.  Kew  describes  the  following  forms:  Encope  tenuis  n.  sp., 
Clypeaster  deserti  n.  sp.,  C  carrizoensis  n.  sp.,  C.  bowersi  Weaver,  Hipponoe  californica  n.  sp.,  and  Cidaris  sp. 


EOCENE  ECHINODERMATA. 

Class  CRIXOIDEA. 

Subclass  DICYCLICA. 

Order  FLEXIBILIA. 

Suborder  PINNATA. 

Family  ANTEDONID^. 

Genus  ZENOMETRA  A.  H.  Clark. 

Zenometra   (?)  CONOIDEUS   (Emnions). 

Microcrinus  conoideiis  Emmons,  1858,  Agriculture  Eastern  Counties:  North  Carolina  Geol.  Survey  Eept. ,  p.  311,  figs.  246, 

247. 
Microcrinus  conoideus  Conrad,  1866,  Check  list,  Eocene  and  Oligocene,  p.  31. 

Description. — The  descriptions  and  figures  of  this  form  by  Emmons  are  very  inadequate. 
Springer,  who  kindly  examined  them  for  the  author,  says: 

Emmons's  figiires  represent  the  centro-dorsal  of  a  comatulid,  broken  away  from  the  radials,  prcser\-ing  the  "  rosette  " 
filled  with  matrix,  and  the  "  basal  rays."  The  latter  indicate  noncontiguous  basals — a  character  which  removes  it  from 
Atelocrinus.  The  regular  arrangement  of  cirrus  sockets  in  columns,  combined  with  the  large  central  cavity  of  the  cen- 
trodorsal,  places  it  in  the  family  Antedonidae,  as  restricted  by  Mr.  A.  H.  Clark,  and  it  might  belong  to  a  form  like  his 
genus  Zenometra,  recent  species  of  which  occur  in  the  Atlantic  and  Caribbean  from  the  Carolinas  to  St.  Lucia.  Without 
the  superior  parts  of  the  calyx  it  is  impossible  to  make  closer  comparison,  and  it  miist  remain  among  the  imperfectly 
known. 

No  specimens  have  been  secured  in  recent  collecting  and  no  material  representing  this  spe- 
cies has  been  found  in  any  museum. 

Locality. — Craven  County,  N.  C.  (Emmons). 
Geologic  horizon. — Trent  marl,  middle  Eocene. 
Collection. — ^Unknown. 

Class  STELLEROIDEA. 

Subclass  ASTEROIDEA. 

Order  CRYPTOZONIA. 

Family  ASTERIID.E. 

Genus  ASTERIAS  Linne. 
AsTEKIAS    (?)    sp. 
Asterias  Morton,  1834,  Sjiiopsis  Organic  Remains  Cretaceous,  p.  74. 

Description. — Morton  saj^s :  "I  have  seen  but  a  few  obscure  fragments  of  this  genus,  from 
the  calcareous  strata  of  South  Carolina."  It  is  quite  impossible  without  authentic  specimens  to 
determine  whether  the  material  in  Morton's  hands  belongs  to  this  genus  or  not. 

Locality. — South  Carolina. 

Geologic  Jiorizon.— 'Eocene. 

Collection. — ^Unknown. 
112 


EOCENE   ECHINODEEMATA.  113 

Class  ECHINOIDEA. 

Subclass  REGUT.AKIA  ENDOBRANCHIATA. 

Order  CIDAROIDEA. 

Family  CIDARID.E. 

Genus  CIDABIS  Leske. 

CiDARis  MiTCHELLi  Einmons. 

Plate  LV,  figures  la-fc. 

Cidaris  mitchelli  Emmons,  1858,  Agriculture  Eastern  Counties:  Kept.  North  Carolina  Geol.  Survey,  p.  305,  fig.  237. 
Cidaris  mitchelli  Conrad,  1866,  Check  list,  Eocene  and  Oligocene,  p.  3. 
Cidaris  mitchelli  Heilprin,  1884,  Contrib.  Tertiary  geology,  p.  17. 
Cidaris  mitchelli  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  693. 

Determinative  characters. — Test  large,  thick,  and  of  moderate  height.  Ambulacra  rather 
broad,  somewhat  undulating  with  four  to  six  rows  of  granules  between  the  poriferous  avenues. 
Interambulacra  wide  with  9  to  10  plates  in  each  row,  each  plate  bearing  a  single  large  circular 
tubercle  the  areola  of  which  is  sm-rounded  by  a  row  of  small  tubercles.  Miliary  space  covered 
with  numerous  thickly  radiated  granules.  ^ 

Dimensions. — Diameter  53  miUimeters;  height  32  milUmeters. 

Description. — The  species  is  represented  by  a  single  specimen,  the  type  described  by 
Emmons,  which  in  many  particulars  is  in  an  excellent  state  of  preservation.  The  test  is  large, 
thick,  and  circular  in  outhne.     It  is  of  medium  height. 

The  ambulacra  are  rather  broad  and  somewhat  undulating,  with  four  rows  of  granules 
between  the  poriferous  avenues  toward  the  apical  system  and  peristome,  but  with  six  rows  on  the 
ambitus.     The  pores  are  oral  and  connected  by  deep  furrows. 

The  interambulacra  are  wide  and  bear  two  rows  of  large  circular  tubercles,  the  areolas  of 
which  closely  approach  each  other  and  are  covered  by  a  row  of  small  tubercles.  The  tubercles 
are  round,  depressed,  and  have  much  elevated  and  deeply  peiforated  mamelons. 

Related  forms. — The  species  is  most  closely  related  to  0.  carolinensis  but  is  somewhat  lower, 
the  granules  on  its  miliary  space  are  smaller  and  differently  distributed  and  its  tubercles  approach 
each  other  more  closely.  Its  areolas  have  a  surrounding  row  of  small  tubercles  which  are  absent 
in  C.  carolinensis. 

Locality. — Craven  County  (?),  N.  C.  (Emmons). 

Geologic  horizon. — Trent  marl,  middle  Eocene. 

Collection. — WiUiams  College. 

Cidaris  carolinensis  Emmons. 

Plate  LV,  figures  2a-c. 

Cidaris  carolinensis  Emmons,  1S5S,  Agriculture  Eastern  Counties:  North  Carolina  Geol.  Survey  Kept.,  pp.  305-306, 

fig.  238. 
Cidaris  carolinensis  Conrad,  1866,  Check  list.  Eocene  and  Oligocene,  p.  31. 
Cidaris  carolinensis  Heilprin,  1884,  Contrib.  Tertiary  geology,  p.  17. 
Cidaris  carolinensis  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  698. 

Determinative  characters. — Test  large,  thick,  and  rather  tall.  Ambulacra  rather  broad, 
somewhat  undulating,  with  four  rows  of  granules  between  the  poriferous  avenues.  Interambu- 
lacra wide,  each  with  two  rows  of  large  circular  tubercles,  10  to  11  in  each  row.  Mihary  sjjace 
covered  with  numerous  thickly  set  granules. 

Dimensions. — Diameter  60  millimeters;  height  35  millimeters. 

Description. — The  type  specimen  of  Emmons  is  the  only  representative  of  this  species  that 
has  been  available  for  study.  Although  somewhat  crushed  the  portions  preserved  are  in  an 
excellent  state  of  preservation.  The  test  is  of  rather  large  size,  thick,  and  somewhat  taller  than 
in  most  species  of  Cidaris. 


114  MESOZOIC    AND   CEKOZOIC   ECHIKODEEMATA   OF    THE    UNITED   STATES. 

The  ambulacra  are  rather  wide  and  somewhat  undulating,  with  four  rows  of  granules  between 
the  poriferous  avenues  on  the  upper  and  lower  surfaces,  which  become  increased  to  six  at  the 
ambitus.     The  pores  are  oval  m  shape. 

The  interambulacra  are  wide,  each  with  two  rows  of  large  circular  tubercles  that  however 
leave  a  wide  miliary  space  on  each  plate  that  is  thickly  set  with  granules  of  very  uniform  size 
throughout.  The  tubercles  are  round  and  deeply  depressed.  The  boss  is  smooth  and  the  mame- 
lons  deeply  perforated. 

Related  forms. — This  species  is  closely  related  to  C.  mitcheUi  but  is  evidently  taller  and  has 
larger  granules  somewhat  differently  dispersed.  Its  tubercles  are  more  widely  separated  than 
those  of  C.  mitcheUi,  and  its  areolas  lack  the  surrounding  row  of  small  tubercles. 

Locality. — Craven  County  (?),  N.  C.  (Emmons). 

Geologic  horizon. — Trent  marl,  middle  Eocene. 

Collection. — Williams  College. 

CiDARis  PEATTi  Clark,  n.  sp. 
,  Plate  LV,  figure  3. 

Determinative  characters. — Test  small,  thin,  rather  high,  circular.  Ambulacra  narrow 
nndulatmg,  two  rows  of  granules  between  the  poriferous  avenues;  pores  nearly  round.  Inter- 
ambulacra wide,  each  with  two  rows  of  tubercles;  each  tubercle  round,  depressed,  with  crenu- 
lated  boss  and  perforated  mamelon  and  wdth  areolas  surrounded  by  row  of  small  tubercles. 

Dimensions. — Diameter  18  (?)  milhmeters;  height  15  (?)  millimetei-s. 

Description. — The  only  specimens  available  for  study  consist  of  fragments  of  tests,  chiefly 
of  detached  plates.     The  test  is  small  and  thin,  rather  high,  and  apparently  circular  in  outline. 

The  ambulacra  are  naiTow  and  undulating.  The  pores  are  nearly  round.  Two  rows  of 
small  granules  occur  between  the  poriferous  avenues. 

The  interambulacra  are  -wide,  each  with  two  rows  of  tubercles  which  largely  occupy  the  area 
of  the  plates.  The  miliary  space  is  very  small  and  covered  with  granules.  Each  tubercle  has  a 
depressed  areola  surrounded  by  a  row  of  small  tubercles.  The  boss  is  crenulated  and  the  mame- 
lon perforated. 

Related  forms. — The  species  is  unique  and  difl'ers  widely  from  the  other  Tertiary  species. 
It  is  more  closely  related  to  C  mitcheUi  than  to  0.  carolinensis. 

Locality. — Wilmington,  N.  C. 

Geologic  horizon. — Castle  Hayne  limestone,  upper  Eocene  or  Oligocene. 

Collection.^U.  S.  National  Museum  (164663). 

CiDARis  MERRiAMi  Arnold. 
Plate  LV,  figure  4. 

Cidarismerriami  Arnold,  1908,  U.  S.  Nat.  Mua.  Proc,  vol.  34,  p.  359,  PL  XXXII,  fig.  8. 
Cidaris  merriami  Stetanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  696. 

Determinative  characters. — Test  wanting.  Spine  subcixcular  in  cross  section,  tapering  slightly; 
surface  with  13  or  14  prominent  ribs  separated  by  narrow  grooves;  nodes  well  defined. 

Dimensions. — Longest  fragment;  length  20  millimeters;  maximum  diameter  4.5  milli- 
meters. 

Description. — Arnold,  in  his  description  of  tliis  species,  says: 

The  test  of  this  species  is  urLknovrn,  but  the  abundance  and  well  marked  characteristics  of  the  fragments  of  the 
spines  has  been  deemed  of  enough  importance  to  justify  a  specific  name.  Seven  specimens  have  been  obtained  at  the 
type  locality,  each  showing  the  characters  described  above. 

Spines  subcircular  in  cross  section,  as  much  as  4  millimeters  in  diameter  and  probably  over  40  miUimeters  in 
length,  tapering  very  slightly;  surface  sculptured  by  13  or  14  prominent,  narrow,  nodose,  ridgelike,  longitudinal  ribs 
separated  by  narrow,  deeply  incised  grooves;  the  nodes  are  well  defined,  especially  in  the  younger  stages  of  growth,  and 
are  subelliptical  in  cross  section,  their  longer  axis  being  parallel  with  the  axis  of  the  spine. 


EOCENE   ECHINODEKMATA.  115 

H.  L.  Clark,  who  examined  the  specimens  for  Arnold,  says  that  they 

All  appear  to  belong  to  one  species,  except  possibly  one  fragment.  That  piece  might  possibly  have  come  from  quite 
a  different  species.  I  am  very  glad  to  see  this  material  of  merriami,  for  it  satisfies  me  that  the  species  must  have  been 
allied  to,  not  identical  with,  Trctocidaris  perplexa  Clark  (Cidaridse,  1907,  p.  205,  PI.  VI,  figs.  1-2;  PI.  VII,  figs.  1^)  the 
only  other  living  littoral  cidarid  known  from  north  of  Panama  (other,  I  mean,  than  thouarsii).  So  your  material 
shows  that  the  ancestors  of  l)Oth  thouarsii  and  perplexa  lived  in  the  Tertiary  in  California. 

Locality. — Santa  Cruz  quadrangle,  San  Mateo  County,  locality  No.  25,  ridge  between  head- 
waters of  San  Lorenzo  River  and  Pescadero  Creek,  Cal. 

Geologic  horizon. — Eocene,  ]5ossible  equivalent  of  Martinez  formation. 
Collection.— V.  S.  National  Museum  (165,  438). 

CiDARis  MCEREUS  De  Gregorio. 

Cidaris  mcereus  De  Gregorio,  1890,  Mon.  faune  ^oc^nique  Alabama,  p.  252,  PI.  XLIII,  figs.  22-23 
Cirfan's TOcerews  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Description. — No  specimens  of  this  species  were  available  for  study.  The  type  form  described 
by  de  Gregorio  evidently  came  with  other  materials  from  the  Claiborne  in  Alabama.  The  author 
describes  the  species  as  follows:  "Aculeus  subcylindraceus,  oblongus,  tuberculis  erectis  notatis 
confertis  majoribus  et  minoribus  irregulariter  dispositis  ornatus." 

Locality. — Near  Claiborne,  Ala. 

Geologic  horizon. — Claiborne  group,  middle  Eocene. 

Collection. — De  Gregorio. 

Cidaris  modestus  De  Gregorio. 

Cidaris  modestus  De  Gregorio,  1890,  Mon.  faune  6oc6nique  Alabama,  p.  253,  PL  XLIII,  fig.  26. 
Cidaris  modestus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Description. — No  specimens  of  this  species  were  available  for  study.  The  type  form  de- 
scribed by  De  Gregorio  evidently  came  with  other  materials  from  the  Claiborne  in  Alabama. 
The  author  describes  the  species  as  follows:  "Aculeus  augustus,  conoideo-cylindraceus,  costuUs 
longitudinalibus  ornatus;  costis  crenulatis,  granulo-squamosis ;  granulis  subimbricatis." 

Locality. — Near  Claiborne,  Ala. 

Geologic  horizon. — Claiborne  group,  middle  Eocene. 

Collection. — De  Gregorio. 

Cidaris  ordinatus  De  Gregorio. 

Cidaris  ordinatus  De  Gregorio,  1890,  Mon.  faune  ^ocenique  Alabama,  p.  352,  PI.  XLIV,  fig.  1. 
Cidaris  ordinatus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Description. — No  specimens  of  the  species  were  available  for  study.  The  type  form  described 
by  De  Gregorio  evidentl}'  came  with  other  materials  from  the  Claiborne  group  near  Claiborne, 
Ala.  The  author  describes  the  species  as  follows :  "Aculeus  subcylindraceus;  tuberculis  erectis, 
raris,  subsequalibus,  quincuncim  atque  spu'aliter  regulariter  dispositis." 

Locality. — Near  Claiborne,  Ala. 

Geologic  horizon. — Claiborne  group,  middle  Eocene. 

Collection. — De  Gregorio. 


116  MESOZOIC   AND  CENOZOIC   ECHINODEEMATA   OP   THE   UNITED   STATES. 

CiDARis  PERDUBius  De  Gregorio. 

Cidaris  perdubius  De  Gregorio,  1890,  Mon.  faune  6ocenique  Alabama,  p.  253,  PI.  XLIV,  fig.  2. 
Cidaris perdubius  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Description. — No  specimens  of  this  species  were  available  for  study.  The  type  form 
described  by  De  Gregorio  evidently  came  with  other  materials  from  the  Claiborne  in  Alabama. 
The  author  describes  the  species  as  f ollov/s :  ' '  Aculeus  cylindraceus  potius  augustus,  tenu  tuber- 
culatus;  tuberculis  densis,  parvis,  in  series  longitudinales  recte  dispositis." 

Locality. — Near  Claiborne,  Ala. 

Geologic  Iwrizon. — Claiborne  group,  middle  Eocene. 

Collection. — De  Gregorio. 

CiDAKis  BLANDis  De  Gregorio. 

Cidaris  blandis  De  Gregorio,  1890,  Mon.  faune  eocenique  Alabama,  p.  253,  PI.  XLIV,  fig.  4. 
Cidaris  blandis  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Description. — No  specimens  of  this  species  were  available  for  study.  The  type  form 
described  by  De  Gregorio  evidently  came  with  other  materials  from  the  Claiborne  group  near 
Claiborne,  Ala.  The  author  describes  the  species  as  follows:  "Aculeus  augusta,  conoideo- 
cjdindraceus,  costulis  longitudinalibus  ornatus;  costis  crenulatis,  granulo-squamosis ;  granulis 
subimbricatis." 

Locality. — Near  Claiborne,  Ala. 

Geologic  horizon. — Claiborne  group,  middle  Eocene. 

Collection. — De  Gregorio. 

Cidaris  alabamensis  Morton. 

Cidaris  alabamensis  Morton,  1846,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  3,  p.  51. 
(?)  Cidaris  sp.  Aldrich,  1886,  Alabama  Geol.  Survey  Bull.  1,  p.  43. 
Cidaris  alabamensis  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Description. — No  material  has  been  obtained  that  can  be  regarded  as  belonging  to  this 
species,  which  Morton  very  inadequately  describes  and  which  he  does  not  figure.  Morton  in  his 
description  says  that  this  species  is  "Compressed,  pentagonal,  the  angles  rounded  so  as  to  form 
a  10-sided  figure.  Ten  rows  of  tubercles,  with  9  or  10  in  each  row.  Ambulacra  arranged  in 
five  pau's,  with  delicate,  shghtly  oblique  fissures  separated  by  a  double  elevated  line.  Surface 
between  the  tubercles  and  ambulacra  finely  granulated."  Morton  states  that  the  specimen 
described  was  found  in  the  "Eocene  strata  of  Washington  County,  Ala.,"  but  if  it  was  derived 
from  the  St.  Stephens  limestpne,  as  seems  probable,  it  may  be  Oligocene,  for  the  upper  beds  are 
of  that  age. 

Locality. — Washington  County,  Ala.  (Morton). 

Geologic  horizon. — St.  Stephens  (?)  limestone.  Eocene  (?). 

Collection. — Unknown. 

Cidaris  sp. 

Cidaris  sp.  De  Gregorio,  1890,  Mon.  faune  Eocenique  Alabama,  p.  252. 

Description. — The  material  representing  this  species  is  referred  to  by  De  Gregorio  in  these 
words:  "Auctor  nullam  descriptionem  hujus  specei  dat."     No  figure  is  given. 

Locality. — Near  Claiborne,  Ala. 

Geologic  horizon. — Claiborne  group,  middle  Eocene. 

Collection. — De  Gregorio. 


EOCENE   ECHINODERMATA.  117 

Subclass  REGUT^ARIA  ECTOBRANCHIATA. 

Order  DIADEMOIDEA. 

Suborder  ARBACINA. 

Family  ARBACIID.E. 

Genus  CCELOPIiEUBUS  Agassiz. 

CtELOPLETTRUS    INFULATUS    (Moi'toil). 

Plate  LVI,   figures  la-i. 

Echinus infulatiis  Morton,  1833,  Am.  Jour.  Sci.,  Istser.,  vol.  24,  p.  131,  PL  X,  fio:.  7. 
Echinus  infulatus 'Morton,  1834,  Synopsis  Organic  Remains,  p.  75,  PI.  X,  fig.  7. 
Echinus  infulatus  Morton,  1842,  Acad.  Nat.  Sci.  Philadelplua  Jour.,  1st  ser.,  vol.  8,  p.  217. 
Echinus  infidatus  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  450;  vol.  2,  p.  187. 
Echino-cidari-s  infulatus  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 
(?)  Arbacia  (?)  sp.  Bouv^,  1851,  Boston  Soc.  Nat.  Hist.  Proc,  vol.  4,  p.  3. 
Cmlopleunis  infulatus  Desor,  1858,  Sy^iopsis  des  ^chinides  fossiles,  p.  98. 
Echinus  infulatus  Gabb,  1859,  Cat.  Invertebrate  Fossils  Cretaceous,  p.  19. 
C(£lopleurus depressus  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  23,  p.  74. 
Ccelopleurus  infulatus  Conrad,  1866,  Check  list.  Eocene  and  Oligocene,  p.  22. 
Ccelopleurus  depressus  Conrad,  1866,  Check  list,  Eocene  and  OHgocene,  p.  22. 
Cxlopleurus  (Echinus)  inflatus  A.  Agassiz,  1874,  Revision  of  the  Echini,  p.  751. 
Echinus  infulatus  ?  Aldrich,  1886,  Alabama  Geol.  Survey  Bull.  1,  p.  43. 
Cwlopleurus  infulatus  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Echinus  infulatus  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  118. 
Ccelopleurus  infulatus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  698. 
Ccelopleurus  depressus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  698. 

Determinative  characters. — Test  moderate,  depressed.  Aml^ulacra  narrow,  projecting  on 
upper  surface,  with  two  rows  of  tubercles  extending  from  the  peristome  to  the  apical  system, 
plates  compound  except  near  apex;  poriferous  avenues  narrow;  pore  pairs  uniserial,  ixi  arcs. 
Interambulacra  broad,  each  with  four  rows  of  primary  tubercles  extending  from  the  peristome 
to  slightly  above  the  ambitus  beyond  which  the  inner  rows  disappear.  Apical  system  large, 
the  genital  plates  in  contact.  Peristome  with  small  branchial  incisions.  Periproct  large 
subpent  agonal. 

Dimensions. — Diameter  19.5  millimeters;  height  10  miUimeters. 

Description. — This  very  characteristic  species  is  represented  by  a  single  specimen  from  the 
Santee  marl  member  of  the  McBean  formation  of  South  Carolina.  The  test  is  of  moderate 
size,  depressed  and  subpentagonal  in  outline. 

The  ambulacra  are  narrow  and  project  above  the  general  level  of  the  test.  Each  am- 
bulacrum has  two  rows  of  prbnary  tubercles  that  extend  from  the  peristome  nearly  to  the 
apex.  The  tubercles  are  imperforate  and  noncrenulate.  The  j^lates  are  compound  except 
near  the  apex  and  consist  of  one  primary  and  two  demiplates.  The  poriferous  avenues  are 
narrow,  and  the  pore  pairs  which  are  uniserial  are  in  arcs. 

The  interambulacra  are  broad,  each  area  being  covered  with  four  rows  of  primary  tubercles 
which  extend  from  the  peristome  to  a  little  above  the  ambitus,  beyond  which  the  two  central 
rows  disappear,  and  the  outside  rows  gradually  decliae  in  size  to  very  small  tubercles  or  even 
into  granules.     The  large  bare  median  area  produces  a  broad  depression  on  the  upper  surface. 

The  apical  system  is  large,  the  genital  plates  coming  into  contact  and  separating  the  small 
oculars. 

The  i^eristome  is  large  with  small  branchial  incisions.  The  periproct  is  large  and  subpen- 
tagonal in  outline. 

Locality. — South  Carolina  (Morton). 

Geologic  Tiorison. — Santee  marl  member  of  .McBean  formation,  of  Claiboi-ne  group,  middle 
Eocene. 

Collection. — -Academy  of  Natural  Sciences  of  Philadelphia  (1076). 


118  MESOZOIC   AND   CEXOZOIC    ECHIXODEKMATA    OF    THE    UKITED    STATES. 

Suborder  DIADEMINA. 
Family  CYPHOSOMATID.f:. 

Genus  OBTHECHINTJS  Gauthier. 

Oethechinus  pretiosus  Clark,  n.  sp. 

Plate  LVI,  figures  2  a-b. 

Determinative  cJmracters. — Test  small,  depressed,  circular.  Ambulacra  wide,  with  two  rows 
of  low  primary  tubercles,  crenulate  and  imperforate;  poriferous  avenues  straight,  pore  pairs 
uniserial,  with  three  pairs  to  each  plate.  Interambulacra  with  two  rows  of  primary  tubercles 
similar  to  those  of  ambulacra  and  with  additional  smaller  tubercles  and  granules.  Apical 
system  large.     Periproct  large. 

Dimensions. — Diameter  20  millimeters;  height  8  mUUmeters. 

Description. — A  single  crushed  specimen  of  this  species  has  been  found.  The  test  is  small 
depressed,  and  circular  in  ambital  outline.  The  ambulacra  are  -n-ide  with  two  rows  of  crenulate 
and  imperforate  small  primary  tubercles,  whicli  are  somewhat  indistinct  on  account  of  their 
relatively  small,  low  mamelons  and  small  areolas.  Smaller  tubercles  and  granules  axe  also 
found.  The  poriferous  avenues  are  straight,  the  pore  pairs  uniserial  with  three  pairs  to  each 
compound  plate. 

Tiie  interambulacra  have  two  rows  of  primary  tubercles  similar  to  the  ambulacra  together 
with  smaller  tubercles.     The  miliary  space  is  covered  ■\\-ith  irregularly  dispersed  granules. 

The  apical  system  is  large,  pentagonal  in  outline,  and  wath  large  genital  plates.  The 
periproct  is  large. 

Locality. — Dead  Level,  Choctaw  County,  Ala. 

Geologic  Jiorizon. — St.  Stephens  limestone  (lower  portion),  upper  Eocene. 

Collection.— v.  S.  National  Museum  (146455). 

Suborder  ECHININA. 
Family  TRIPLECHINIDiE. 

Genus  ECHINUS  Linne. 

Echinus  exerceus  De  Gregorio. 

?  Echinus  sp.  Aldrich,  1886,  Alabama  Geol.  Survey  Bull.  1,  p.  49. 

Echinus  exerceus  De  Gregorio,  1890,  Alabama  Mon.  faune  eocenique,  p.  252,  PI.  XLIV,  fig.  3. 

Echinus  exerceus  Stefanini,  1911,  Soc.  geol.  itaUana  BoU.,  vol.  30,  p.  G97. 

Description. — No  material  representing  this  species  was  available  for  study.  De  Gregorio 
gives  the  following  description:  "Aculeus  exilis,  oblongus,  sub  lente  minutissime  eleganter 
punctulatus  reticulatusque,  interne  ad  basim  turgidus." 

Locality. — Near  Claiborne,  Ala.  (De  Gregorio). 

Geologic  horizon. — Claiborne  group,  middle  Eocene. 

Collection. — De  Gregorio. 

Echinus  (?)  sp. 

Plate  LVI,  figure  3. 
Diadematoid  spines,  Clark  and  Martin,  1901,  Maryland  Geol.  Survey,  Eocene,  p.  232,  PI.  LXI,  fig.  2. 

Description. — Several  small,  thin  ecliinoid  spines,  the  generic  relations  of  wliich  can  not  be 
with  certainty  determined,  have  been  found  in  the  Eocene  deposits  of  Maryland  and  Virginia. 
They  are  doubtfully  refeiTed  to  Echinus. 

Localities. — Near  South  River  and  Severn  River,  Md. ;  Potomr.c  Creek,  Va. 

Geologic  horizon. — Aquia  formation,  lower  Eocene. 

Collection.— Johns  Hopkins  University  (T  2000). 


EOCENE   ECHINODEEMATA.  119 

Subclass  IRREGULARIA. 

Order  GNATHOSTOMATA. 

Suborder  CLYPEASTRINA. 

Family  FIBULARIID.E. 

Genus  ECHINOCYAMUS  Phelsum. 

EcHiNOCTAMUS  PARVUS  Emiiions. 

Echinocyamus  parvus  Emmons,  1858,  Agriculture  Eastern  Counties:  North  Carolina  Cteol.  Survey  Rept.,  p.  307,  fig.  244. 
Echinocyamus  parvus  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  31. 
Echinocyamus  parvus  Heilprin,  1884,  Contrib.  Tertiary  Geology  U.  S.,  p.  17. 
Echinocyamus  parvus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  C98. 

Description  and  determinative  characters. — The  location  of  Emmons's  type  of  this  little 
ecliinoid  is  unknown,  and  the  writer  has  been  unable  to  find  any  specimen  similar  to  it  in  the 
North  Carolina  material  studied.  The  description  of  Emmons  is  therefore  quoted  in  full,  as 
follows : 

Test  small,  oval,  with  rounded  sides,  avenues  dorsal;  mouth  subcentral,  rounded,  large,  with  a  crenulated  margin; 
vent  between  the  mouth  and  hinder  margin ;  genital  pores  apparently  four.  The  mouth  is  large  in  proportion  to  the  size 
of  the  body  and  the  vent  is  situated  halfway  between  the  mouth  and  the  margin. 

Dimensions. — ^Emmons's  figure,  which  he  states  is  natural  size,  is  5  millimeters  in  length  and 
3  millimeters  in  width. 

Related  forms. — E.  parvus  is  closeh'  alhed  to  E.  huxleyanus.  Tlie  latter  apparently  cUffers, 
however,  in  being  more  pointed  anteriorly  and  in  having  the  periproct  near  the  posterior  margin. 
E.  parvus  is  also  closely  related  to  E.  vaughani  and  E.  texanus,  wliich  are  to  be  distinguished  by 
ha'vdng  the  periproct  nearer  the  peristome. 

Locality. — Craven  County,  N.  C.  (Emmons). 

Geologic  horizon. — Eocene  (Emmons).     Very  probably  from  the  Trent  marl. 

Echinocyamus  huxleyanus  Meyer. 

Plate  LVII,  figures  la-d. 

Echinocyamus  huxleyanus  Meyer,  1886,  Alabama  Geol.  Survey  Bull.  1,  p.  85,  PL  III,  fig.  23. 
Echinocyamus  huxleyanus  De  Ciregorio,  1890,  Mon.  faune  eocenique  Alabama,  p.  251,  PI.  XLIII,  fig.  15. 
Echinocyamus  huxleyanus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Determinative  characters. — Test  thin-walled  and  fragile,  very  small,  flattened  egg-shaped, 
anterior  end  pointed.  Upper  surface  low,  convex;  under  surface  concave  around  peristome. 
Apical  system  excentric  anteriorly,  with  four  large  genital  pores.  Petals  rudimentary,  open  at 
ends;  pores  not  conjugated.  Peristome  central,  relatively  large.  Periproct  small,  about  one- 
fourth  the  distance  from  margin  to  peristome.     Tubercles  relatively  large. 

Dimensions. — Length  3  to  5  milUmeters;  width  2  to  3  milhmeters;  height  1  to  2  milHmeters. 

Description. — This  httle  EcMnocyamus  is  found  in  some  abundance  in  the  sands  of  the 
Claiborne  group  in  Alabama.  The  test  is  notably  thin-walled  and  fragile,  in  strong  contrast 
with  the  other  American  representatives  of  the  genus.  In  marginal  outline  it  is  subelhptical  to 
elongate  subovate  and  in  general  form  subelhpsoidal  to  flattened  egg-shaped ;  the  anterior  end 
being  more  or  less  pointed,  and  the  height  being  about  half  or  less  than  half  of  the  width.  Tlie 
upper  surface  is  low  and  gently  convex;  the  lower  surface  flattened,  sUghtly  concave  close  to  the 
peristome. 

The  ambulacra!  petals  are  rucHmentary,  extending  two-tMrds  or  more  of  the  way  to  the 
margin,  open  at  the  ends;  poiiferous  zones  nearlj-  straight,  pores  round,  pairs  not  conjugated. 
The  apical  system  is  excentric  anteriorly,  ^\-ith  four  large  genital  pores  set  close  together,  the 
anterior  pair  being  only  slightly  nearer  together  than  the  posterior  pair. 


120  MESOZOIC   AND   CENOZOIC    ECHINODEEMAIA   OF    THE    UI^ITED    STATES. 

Tlie  surface  of  the  test  is  covered  with  numerous  small  but  rather  conspicuous  tubercles  set 
in  relativel}'  large  scrobicules. 

The  peristome  is  central,  relatively  large,  circular.  The  periproct  is  small,  about  one-half 
the  diameter  of  the  peristome,  situated  near  the  margin,  being  about  one-fourth  of  the  distance 
from  the  margin  to  the  peristome. 

Related  forms. — E.  huxleyanus  is  closely  related  to  E.  farvus.  In  fact,  it  is  quite  possible 
that  ^vith  the  discovery  of  some  good  specimens  of  Emmons's  form  E.  Tiuxleyanus  may  be  found 
to  be  identical  and  be  reduced  to  a  synonym.  It  appears  to  differ  from  E.  farvus,  however,  in 
having  its  periproct  nearer  the  margin  and  in  being  more  pointed  anteriorly.  It  also  resembles 
both  E.  texanus  and  E.  vaughani,  but  differs  from  them  in  having  tUnner  walls,  in  being  less 
elevated,  and  in  not  ha^'ing  its  periproct  near  the  peristome. 

Locality. — Claiborne,  Ala. 

Geologic  horizon. — Gosport  sand,  Claiborne  group,  middle  Eocene. 

Collections. — U.  S.  National  Museum  (figured  form);  Johns  Hopkins  University  (T  2006). 

EcHiNOCYAMUS  TEXANUS  Twitchell,  n.  sp. 
Plate  LVII,  figures  2a-d. 

Determinative  characters. — Test  very  small,  elhpsoidal,  oval  in  marginal  outUne.  Upper 
surface  elevated,  somewhat  flattened  in  the  center;  lower  surface  flattened  around  the  nearly 
flush  peristome.  Apical  system  with  four  medium-sized  genital  pores;  madreporite  tumid. 
Petals  loiig,  the  anterior  three  nearly  reacliing  the  margin,  wide  open  at  ends.  Peristome 
relatively  large,  central;  periproct  very  small,  close  to  peristome. 

Dimensions. — Length  5  milhmeters;  width  4  milUmeters;  height  2.5  milhmeters. 

Description. — Only  a  single  specimen  of  this  new  Ecliinocyamus  has  been  discovered.  It 
was  found  by  Mr.  T.  H.  Aldrich  of  Birmingham,  Ala.,  who  reports  that  it  was  found  in  the 
"Lower  Claiborne"  deposits  of  Lee  County,  Tex.  Tlie  test  is  tliick-walled,  very  small  (it  being 
one  of  the  smallest  of  American  echinoderms),  regularly  oval  in  marginal  outline,  and  elhpsoidal 
in  general  form.  The  upper  surface  is  elevated,  somewhat  flattened  centrally;  the  lower  sur- 
face flattened  near  the  nearly  flush  peristome  and  the  periproct. 

Tlie  ambulacral  petals  are  rather  well  defined,  relatively  long,  all  of  about  equal  length, 
the  anterior  three  extending  nearly  to  the  margin  as  seen  from  above.  The  poriferous  zones 
diverge  in  almost  straight  hues  to  the  ends  where  they  are  wide  apart;  they  consist  of  small 
round  pores  in  pairs  which  are  apparently  not  conjugated. 

Tlie  apical  sj^stem  is  subcentral  or  very  sUghtly  excentric  anteriorly,  coincident  with  the 
apex,  with  four  moderate- sized  genital  pores  set  near  together,  the  anterior  pair  but  shghtly 
nearer  together  than  the  posterior  pair.  A  small,  swollen,  button-shaped  madreporite  just 
reaches  to  the  genital  pores. 

The  peristome  is  relatively  large,  central,  nearly  flush  with  the  lower  surface;  periproct 
very  small,  about  one-third  of  the  diameter  of  the  peristome,  and  is  situated  at  a  distance  from 
the  peristome  equal  to  its  own  diameter. 

Related  forms. — E.  texanus  is  most  closely  related  to  E.  vaughani,  but  is  easily  distinguished 
from  it  by  its  less  egg-shaped  form,  smaller  size,  less  pointed  anterior  end,  and  less  difference 
between  its  longitudinal  and  transverse  diameters.  E.  texanus  also  resembles  E.  parvus  and 
E.  huxleyanus  but  differs  from  both  in  having  its  periproct  near  the  peristome.  It  also  differs 
from  E.  huxleyanus  in  being  less  fragile,  less  depressed,  and  less  pointed  anteriorly. 

Locality. — Lee  County,  Tex. 

Geologic  horizon. — Lower  part  of  Claiborne  group,  middle  Eocene. 

Collection. — Johns  Hopkins  University  (T  2002). 


EOCENE   ECHINODEEMATA.  121 

Genus  SISMONDIA  Desor. 
SiSMONDiA   (?)  PLANA  Coiirad. 
Plate  LVII,  figures  4a-d. 

Sismondia  plana  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  75. 
Mortonia  (Periarchus)  pla7ia  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  21. 
jSismondia  plana  Cotteau,  1S91,  Paleontologie  frangaise,  Echinides  ^ocfenes,  vol.  2,  p.  299. 
Monostychia  plana  Gregory,  1891,  Geol.  Soc.  America  Bull.,  vol.  3,  p.  108. 
Periarchus  (?)  plana  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  699. 

Determinative  characters. — Test  very  small,  very  tliin,  subovate  to  subcircular  in  marginal 
outline,  rounded  to  somewhat  pointed  anteriorly  and  posteriorly.  Upper  surface  verj^  low, 
slightly  tumid  centrally;  apex  and  apical  system  more  or  less  anteriorly  excentric;  lower  sur- 
face flat;  margin  very  thin.  Ambulacral  petals  subelliptical,  extending  halfway  to  margin, 
nearly  closing  at  ends.  Peristome  slightly  excentric  anteriorly,  small,  circular;  ambulacral 
grooves  well  defined  and  simple  halfway  to  the  margin,  then  obscure  but  apparently  not  branch- 
ing.    Periproct  very  small,  elliptical,  about  two-fifths  the  way  from  margin  to  peristome. 

Dimensions. — Length  17  milUmeters;  width  15  milUmeters;  height  2  millimeters. 

Description. — Tlie  test  of  this  species  is  very  small,  rarely  exceeding  one-half  an  inch  in 
diameter,  very  tliin  throughout,  subovate  to  subcircular  in  marginal  outUne,  rounded  to  some- 
what pointed  anteriorly  and  posteriorly,  broadest  back  of  the  middle.  Tlie  upper  surface  is 
very  low,  shghtly  tumid  centrally;  the  apex  usually  excentric  anteriorly,  sometimes  subcentral; 
the  lower  surface  flat;  the  margin  very  thin. 

The  ambulacral  petals  are  well  defined  but  small,  extending  onlj'  halfway  to  the  margin, 
broadly  lanceolate  to  subelhptical  in  outhne,  nearly  closing  at  the  ends ;  several  pairs  of  pores 
extend  beyond  the  ends  of  the  petals.  The  poriferous  zones  are  relatively  narrow,  inner  row 
of  pores  round,  outer  row  oval,  pairs  of  pores  conjugated;  interporiferous  areas  rather  narrow, 
not  much  wider  than  the  poriferous  zones. 

The  apical  system  is  subcentral  or  excentric  anteriorly,  coincident  with  the  apex.  Tlie 
details  could  not  be  clearly  niade  out  on  the  specimens. 

Tlae  tuberculation  is  inconspicuous,  the  whole  test  being  covered  with  small  tubercles,  in 
shallow  scrobicules,  set  closely  together. 

The  peristome  is  subcentral  or  shghtly  excentric  anteriorly,  small,  circular.  The  ambula- 
cral grooves  extend  as  well  defined  simple  Hues  from  the  peristome  haHway  to  the  margin,  beyond 
wliich  point  they  become  obscure;  but  do  not  appear  to  branch. 

Tlie  periproct  is  very  small,  elliptical,  the  longest  diameter  being  longitudinal,  located  about 
two-fifths  of  the  way  from  the  margin  to  the  peristome. 

Related  forms. — Scutella  (?)  conradi  is  closely  related  to  Sismondia  ( ?)  flana  but  differs  from 
it  in  having  its  posterior  border  truncated  and  notched  at  the  middle  and  opposite  the  posterior 
petals,  and  its  periproct  nearer  the  posterior  border. 

Locality. — The  type  came  from  South  CaroUna.  (No  more  definite  locality  can  be  given.) 
Some  specimens  came  from  near  Charleston,  S.  C. 

Geologic  Tiorizon. — Eocene. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1080). 

Genus  FIBTJIiARIA  Lamarck. 
FiBULAEiA  MEEiDioNALis  (Meyer). 

Plate  LVII,  figures  3a-d. 

Schinocyamus  meridionalis  Meyer,  1887,  Fauna  Alttertiiirs  Mississippi  und  Alabama,  p.  12,  PI.  II,  figs.  21,  21a. 
Echinocyamus  meridionalis  De  Gregorio,  1890,  Mon.  faune  eoc^nique  Alabama,  p.  251,  PI.  XLIII,  fig.  14, 
Echinocyamus  meridionalis  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  697. 

Determinative  characters. — Test  thin  walled  and  fragile,  very  small,  discoidal,  broadi}-  oval 
to  subcircular  in  marginal  outline.  Upper  surface  very  low,  flat  or  nearly  so;  sides  rounded; 
lower  surface  slightly  concave.     Apical  system  central  or  subcentral;    petals  rudimentary, 


122  MESOZOIC    AXD    CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

inconspicuous.  Peristome  central,  unusually  large,  much  larger  than  periproct,  circular,  with 
crenulated  margin.     Periproct  very  small,  nearer  to  posterior  margin  than  to  peristome. 

Dimensions. — Length  2  to  4  millimeters;  width  1.5  to  3  millimeters;  height  0.5  to  1  milli- 
meter. 

Description. — This  little  echinoid  occurs  in  comparative  abundance  in  association  with 
EcJiinocijamus  Tiuxleijanus  in  the  Gosport  sand  at  Claiborne,  Ala.,  and  elsewhere.  The  test  is 
thin  walled  and  fragile,  very  small,  rarely  reaching  a  quarter  of  an  inch  in  length,  discoidal  in 
general  form,  broadly  oval  to  subcircular  in  marginal  outline.  The  upper  surface  is  very  low, 
rarely  over  a  millimeter  in  height,  fiat  or  faintly  convex;  the  sides  rounded;  the  lower  surface 
nearly  flat,  or  slightly  concave.  In  a  few  specimens  several  faint  radiating  creases  can  be 
distinguished  on  the  lower  side. 

The  ambulacral  petals  are  decidedly  rudimentarj^,  so  inconspicuous  as  to  be  difficult  to 
discern  on  even  good  specimens ;  short,  extending  less  than  halfway  to  the  margin,  the  poriferous 
zones  nearly  parallel  and  composed  of  very  small  pores  in  pairs  which  are  not  conjugated. 

The  apical  system  is  central  or  subcentral,  usually  broken  out.  The  genital  pores  are  very 
small  and  can  rarely  be  made  out  on  the  specimens. 

The  whole  surface  of  the  test  is  covered  %vith  small  tubercles,  set  in  relatively  large 
scrobicules. 

The  peristome  is  central  and  unusually  large  in  proportion  to  the  size  of  the  test,  its  diameter 
being  4  or  5  times  that  of  the  periproct.  The  periproct  is  very  smaU,  circular,  and  situated  from 
one-fourth  to  one-thii'd  of  the  way  from  the  posterior  margin  to  the  peristome. 

Related  forms. — F.  meridionalis  is  not  closely  related  to  any  other  American  species.  In  its 
fragility,  size,  and  superficial  characteristics  it  resembles  E.  Jiuxleyanus,  but  differs  in  having  a 
more  rudimentary  apical  system  and  ambulacral  petals  and  in  its  very  low,  subcircular,  discoidal 
form. 

Localities. — Claiborne,  Ala.,  and  Jackson,  Miss. 

Geologic  horizon. — Gosport  sand  of  Claiborne  group,  middle  Eocene. 

Collections. — Johns  Hopkins  University  (T  2005) ;  U.  S.  National  Museum. 

FamUy  LAGANID.E. 

Genus  LAGANtTM  BlainviUe. 

Laganum  (?)  CKUSTULOiDEs  (^lorton). 

Plate  LVII,  figures  5a-d,  6a-d. 

Scutella  crustuloides  Morton,  1833,  Am.  Jour.  ScL,  1st  ser.,  vol.  24,  p.  131,  PI.  X,  fig.  8. 

Scutellacrustuloides  Morton,  1834,  Synopsis  Organic  Remains  Cretaceous,  p.  77,  PI.  XV,  fig.  10. 

Scutella  crustuloides  Morton,  1842,  Acad.  Nat.  Sci.  Philadelphia  Jom\,  1st  ser.,  vol.  8,  p.  217. 

Scutella  crustuloides  Bronn,  1848,  Index  Palseontologicus,  vol.  1,  p.  1126;  vol.  2,  p.  196. 

Scutella  crustuloides  Ravenel,  1848,  Echinidse,  recent  and  fossil,  of  South  Carolina,  p.  2. 

Scutella  crustuloides  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 

Sismondia  crustuloides  Desor,  1858,  Synopsis  des  ^chinides,  p.  227. 

Scutella  crustuloides  Gabb,  1859,  Cat.  Invert.  Fossils  Cretaceous,  p.  19. 

Scutella  crustuloides  Dujardin  and  Hup^,  1862,  Histoire  nat.  zoophytes  6chuiodermes,  p.  559. 

Sismondia  crustuloides  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  pp.  74-75. 

Sismondia  crustuloides  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  21. 

Scutella  crustuloides  De  Gregorio,  1890,  Mon.  faune  ^oc^nique  Alabama,  p.  251,  PI.  XLIII,  figs.  24-25  (reprod.  from 

Morton). 
Sismondia  crustuloides  Ootteau,  1891,  Pal6ontologie  frangaise,  Echinides  Eocenes,  vol.  2,  p.  300. 
Scutella  crustuloides  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Scutella  crustuloides  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  262. 
Pcriarchus  (?)  crustuloides  Stefanini,  1911,  Soc.  geol.  itaEana  Boll.,  vol.  30,  p.  699. 

Determinative  characters. — Test  small,  subpentagonal,  suboval  or  subovate  in  marginal  out- 
line. Upper  surface  low,  tumid  centrally;  margin  very  thick,  submarginal  area  flat  or  nearly  so, 
about  the  same  thickness  as  the  margin.  Lower  surface  concave.  Apex  and  apical  system 
slightly  excentric  anteriorly.     Ambulacral  petals  lanceolate,  pointed  and  closed  at  the  ends. 


EOCEJJE   ECHINODEKMATA.  123 

extending  two-tliirds  the  way  to  the  margin;  porifenms  zones  much  narrower  than  interporif- 
eroiis  areas.  Peristome  small,  subpcntagonal,  slightly  excentric  anteriorly;  ambiilacral  grooves 
simple,  straight,  inconspicuous.  Periproct  small,  subcircular,  from  one-fourth  to  one-third  the 
way  from  margin  to  peristome. 

Dimensions. — Specimen  A:  Length  21  luillimeters;  width  26  millimeters;  height  5  milli- 
metei-s.     Specimen  B:  Length  31  miUimetere;  width  26  millimeters;  height  6  millimeters. 

Description. — This  little  echinoid  was  one  of  the  first  reported  from  American  deposits, 
having  been  described  and  figured  by  Morton  as  early  as  1833.  It  is  relatively  somewhat  abun- 
dant in  the  Eocene  deposits  and  has  been  found  in  South  Carolina,  Georgia,  and  Alabama.  The 
test  is  small,  ranging  from  three-quarters  of  an  inch  to  1 J  inches  in  length.  In  marginal  outline 
it  is  rather  variable,  being  subpcntagonal  in  most  specimens  but  suboval  or  subovate  in  some. 
The  whole  form  is  greatly  depressed,  the  upjjer  surface  tumid  centrally,  the  tumid  area  involving 
the  larger  part  or  all  of  the  ambulacral  petals;  the  margin  is  rounded  and  notably  tliickened  all 
around,  though  slightly  less  so  at  the  midcUe  of  the  posterior  end  than  elsewhere,  the  submarginal 
area  flat  or  nearly  so,  as  thick  as  or  more  or  less  thick  than  the  margin.  The  under  surface  is 
decidedly  concave,  the  concavity  reaching  nearly  to  the  margin.  The  apex  is  slightly  excentric 
anteriorly  at  the  summit  of  the  tumid  area. 

The  ambulacral  petals  are  lanceolate  or  elongate  subellij^tical,  pointed  and  practically  closed 
at  the  distal  ends;  the  anterior  pair  slightly  shorter  than  the  other  three,  all  of  them  extending 
about  two-thirds  the  way  to  the  margin.  The  poriferous  zones  are  very  narrow,  much  narrower 
than  the  interporiferous  areas,  sometimes  irregular,  the  inner  ends  poorly  defined,  inner  row  of 
pores  round,  outer  row  slitlike,  pairs  of  pores  conjugated.  The  whole  surface  of  the  test, 
including  the  interporiferous  areas  and  the  apical  region  is  covered  with  rather  conspicuous 
small  tubercles  set  in  deep  scrobicules  which  are  larger  on  the  lower  surface. 

The  apical  system  is  central  or  slightly  excentric  anteriorly  at  the  summit  of  the  tumid  area. 
There  are  four  large  genital  pores,  the  anterior  pair  being  set  closer  together  than  the  posterior 
pair.  The  poriferous  zones  rarely  if  ever  can  be  seen  to  come  together  at  the  proximal  ends,  and 
the  perforations  of  the  radial  plates,  if  they  exist,  can  not  be  discerned. 

The  peristome  is  small,  subpcntagonal,  slightly  excentric  anteriorly;  the  ambulacral  grooves 
are  never  very  distinct  on  even  well  preserved  specimens.  They  appear  to  be  straight,  simple, 
faint  lines  from  peristome  to  near  the  margin,  distinguished  more  by  finer  tuberculation  than 
by  the  existence  of  a  distinct  groove. 

The  periproct  is  small,  about  one-third  the  diameter  of  the  peristome,  subcircular,  situated 
from  one-fourth  to  one-third  the  way  from  the  margin  to  the  peristome. 

Related  forms. —  Of  American  forms  L.  (?)  crustuloides  is  most  closely  related  to  L.  joTinsoni 
which  differs  chiefly  in  being  highei  and  having  a  thicker  margin.  L.{1)  crustuloides  is  also  closely 
related  to  L.  floridanum  which  differs  in  having  a  smaller  petaloidal  area,  a  more  regularly  oval 
marginal  outline,  a  concave  ring  around  the  ends  of  the  petals  and  a  flat  lower  surface. 
Scutella  (?)  conradi  also  resembles  the  present  species  but  differs  in  having  its  margin  thin  and 
posteriorly  truncated  and  notched.  L.  archerensis  and  L.  dalli  both  differ  in  having  flat  lower 
surfaces  and  the  apical  region  but  little  if  any  higher  than  their  thick  margins. 

Of  foreign  forms  the  present  species  is  allied  to  Laganum  reflexum  from  the  Tertiary  of 
Blaye,  France,  which,  however,  is  thinner  posteriorly.  Sismomlia  marginalis  (Des  Moulins) 
Desor  from  the  middle  Eocene  of  France  also  resembles  the  present  form  but  differs  in  having 
petals  which  are  longer  and  more  open  at  the  end. 

Localities. — South  Carolina,  probably  near  Charleston;  near  Bainbridge,  Ga.;  Dothan,  Ala. 

Geologic  horizon. — Jackson  formation,  (probably)  upper  Eocene;  Vicksburg  formation, 
lower  Oligocene. 

Collections. — Boston  Society  of  Natural  History  (SS02a,  A);  U.  S.  National  Museum  (lii4, 
744,  B). 


124  MESOZOIC   AND   CENOZOIC    ECHINODEKMATA    OF    THE    UNITED    STATES. 

Family  SCUTELLID^. 

Genus  SCUTELLA  Lamarck. 

Scutella  Lamarck,  1816  (pars),  Anim.  sans  vert.,  vol.  3,  p.  7. 
Scutella  Lamarck,  1840,  Anim.  sans  vert.,  2d  ed.,  vol.  3,  pp.  275-277. 
Scutella  Agassiz,  1841,  Men.  d'^chinodermes,  vol.  2,  Des  scutelles,  p.  75. 
Echinarachnius  Gray,  non  Leske,  1825  (pars),  Ann.  Phil,  for  1825,  p.  428. 
Echinarachnius  Agassiz,  1872  (pars),  Revision  of  the  Echini,  p.  107. 

The  genus  Scutella  as  here  used  includes  the  greatly  depressed  Scutellidse  without  lunulea 
or  digitations ;  with  central  or  subcentral  apical  system ;  homogeneous  or  slightly  differentiated 
plates;  ambulacral  furrows  bifurcating;  periproct  marginal,  inframarginal,  or  actinal,  but  less 
than  two-fifths  of  the  way  from  the  margin;  and  four  or  five  genital  pores. 

Some  of  the  forms  included  here  are  by  certain  authors  placed  under  Echmarachnius 
Leske.  This  practice  has  not  been  followed  by  the  writer  because  apparently  Echinaracluiius, 
being  founded  m  1778  on  Echinus  placenta  lAnne,  should  replace  the  pre-Lhinean  name  Arach- 
noides  Klein  with  which  placenta  was  first  associated  by  L.  Agassiz  in  1841,  and  because, 
even  if  this  correction  is  made,  the  writer  also  questions  the  giving  of  separate  generic  rank 
to  the  forms  with  a  strictly  marginal  periproct. 

Genus  SCUTELLA  Lamarck. 

Scutella  mississippiensis  Twitchoil,  n.  sp. 
Plate  LIX,  figures  la-f,  2. 

Determinative  characters. — Test  variable  in  size;  subcircular  to  subtriangular  in  marginal 
outline,  broader  than  long,  broadest  posteriorly;  the  whole  form  greatly  depressed,  being  thin 
and  nearly  fiat  around  a  narrow  marginal  area  within  which  it  rises  very  gradually  and  gently 
to  the  low,  central  apex;  margin  thin,  with  a  small  notch  in  the  middle  of  the  posterior  edge; 
under  surface  flat.  Ambulacral  petals  elliptical,  extending  about  half  way  to  the  margin. 
Apical  system  central.  Peristome  small,  circular;  ambulacral  furrows  simple  and  straight  for 
two-thirds  or  more  of  the  way  to  the  margin,  then  apparently  forking  symmetrically.  Periproct 
very  small,  circular,  almost  at  the  ambitus  though  slightly  inframarginal,  at  the  edge  of  the 
notch  in  the  middle  of  the  posterior  margin. 

Dimensions. — 'Specimen  A:  Length  50  millimeters;  width  52.5  millimeters;  height  6 
millimetei-s.     Specimen  B:  Length  52.5  millimeters;  width  7G  millimeters;  height  8  millimeters. 

Description. — 'This  new  Scutella  is  one  of  the  most  abundant  in  the  American  Cenozoic 
deposits.  The  writer  has  had  opportunity  to  examine  several  hundred  specimens.  Nearly  all 
of  these  were  from  the  Eocene  deposits  of  Mississippi,  hence  the  specific  name.  The  test  is 
variable  in  size,  ranging  from  less  than  i  inch  to  over  3  inches  in  diameter  and  from  less  than 
J  to  nearly  h  inch  in  height.  Tlie  marginal  outline  is  also  quite  variable,  ranging  from  circular 
to  subcircular  in  the  younger  forms  to  subtriangular  and  even  transversely  elliptical  in  the 
larger  forms.  The  whole  form  is  much  depressed,  being  thin  and  nearly  flat  around  a  narrow 
marginal  area,  although  slightly  more  so  posteriorly  than  elsewhere,  from  which  it  rises  gradu- 
ally and  gently  to  the  low,  central  apex.  Tlie  margin  is  thin  and  faintly  undulating,  with  a 
small  notch  in  the  middle  of  the  posterior  edge;  the  under  surface  is  flat  except  around  the 
peristome,  whore  it  is  slightly  concave.  Tlie  apex  is  central  or  subcentral,  at  the  summit  of  the 
broad  central  tumid  area.  ' 

The  ambulacral  areas  are  narrow  in  the  petaloid  region  but  wide  in  the  marginal  region 
where  they  are  wider  than  the  interambulacral  areas.  The  dorsal  portions  of  the  ambulacra 
are  petaloid.  The  petals  are  subequal  in  length,  the  odd  petal  slightly  longer  and  narrower 
than  the  rest;  elliptical  in  form,  slightly  oprn  at  the  ends  and  extend  about  half  way  to  the 
margin.     The  poriferous  zones  are  rather  wide,  about  equal  to  the  interporiferous  areas,  though 


EOCENE    ECHINODEEMATA.  125 

varying  somewhat  both  among  tho  petals  on  a  single  specimen  or  on  different  specimens,  being 
slightly  wider,  equal  to,  or  slightly  narrower  than  the  interporiferous  areas;  the  inner  row  of 
pores  oval,  outer  row  slitlike,  pairs  of  pores  conjugated.  A  few  pairs  of  pores  occur  beyond  the 
ends  of  the  petals. 

The  interambulacral  areas  are  large  though  somewhat  smaller  both  between  the  petals  and 
at  tho  margin  than  the  ambulacral  areas.  The  whole  surface  of  the  test  is  covered  with  small 
maiform  tubercles  which  arc  slightly  larger  on  the  under  side. 

Tlie  apical  system  is  subcentral,  at  the  summit  of  the  central  tumid  area.  The  madre- 
porite  is  relatively  large,  occupyuig  the  larger  part  of  the  area  covered  by  the  system,  and  flush 
with  the  surface.  There  are  five  genital  pores  near  the  edge  of  the  madreporite.  One  specimen 
studied  possessed  the  abnormal  feature  of  a  double  posterior  genital  pore.  There  are  five  small 
radial  plates,  each  perforated  by  a  minute  pore. 

Tho  peristome  is  very  small,  not  over  double  the  size  of  the.  periproct,  circrdar,  central  or 
slightly  excentric  posteriorly;  the  ambulacral  furrows  simple  and  straight  for  two-thirds  or 
more  of  the  distance  from  peristome  to  margin,  then  apparently  forking  symmetrically,  each 
pair  of  branches  continuing  almost  to  the  margm.  Tlie  under  side  is  revealed  on  few  specimens, 
and  on  few  can  the  furrows  be  made  out. 

The  periproct  is  very  small,  circular,  almost  at  the  ambitus  though  slightly  uiframarginal, 
situated  at  the  under  and  inner  edge  of  the  notch  in  the  middle  of  the  posterior  margin. 

Related  forms. — S.  mississippiensis  does  not  appear  to  be  closely  related  to  any  other 
American  form.  It  resembles  PeriarcTius  lyelli  in  general  appearance,  and  specimens  have 
doubtless  been  erroneously  labeled  S.  h/elli  in  some  collections;  S.  mississippiensis,  however,  is 
readily  distinguished  by  its  submarginal  periproct,  greater  width,  the  notch  in  its  posterior  edge, 
and  the  fact  that  its  tumid  central  area  involves  nearly  tho  whole  upper  surface.  It  bears  an 
interesting  resemblance  to  the  recent  species  Scutella  parma,  but  differs  from  it  in  having  less 
widely  open  petals,  much  narrower  interporiferous  areas,  a  less  circular  and  more  anteriorly 
pointed  form,  and  in  not  having  its  periproct  exactly  marginal  or  at  the  ambitus. 

Of  foreign  forms  S.  patagonensis  (Desor)  Ortman,  especially  the  "alate"  form  described  by 
Ortman  and  formerly  known  as  Echinarachnius  juliensis  Desor  from  the  Neocene  of  Patagonia, 
appears  to  be  most  closely  related  to  S.  mississippiensis.  It  is  very  similar  in  marginal  outline, 
location  of  periproct,  etc.,  but  differs  in  having  a  less  central  apical  system,  longer  petals,  nar- 
rower interambulacral  areas,  and  in  having  its  ambulacral  furrows  begmning  simply  and  then 
forking  in  symmetrical  curving  branches  almost  mimediately.  S.  subtetragona  De  Grateloup  and 
S.  striatula  M.  de  Serres,  both  from  the  upper  Eocene  of  France,  also  present  certain  points  of 
identity  with  S.  mississippiensis.  Each,  however,  differs  from  the  American  form  in  having 
four  genital  pores  instead  of  five  and  in  having  the  ambulacral  furrows  fork  near  the  peristome. 

Localities. — -Cemetery  Branch  (type),  Radiate  Banks,  SpUlman's  Clam  bed  and  other 
localities  in  and  aroimd  Enterprise,  Clarke  County,  Miss. ;  San  Augustin,  and  1  mile  southwest 
of  Palestine,  Tex. 

Geologic  horizon. — Claiborne  gi'oup,  middle  Eocene.  In  Mississippi,  at  the  base  of  the 
Lisbon  marl.     In  Texas,  in  the  marine  substage  of  the  Claiborne. 

Collections. — U.  S.  National  Museum  (1.37655,  A;  137655a,  B);  Wagner  Free  Institute  of 
Science. 

Scutella  tuomeyi  Twitchell,  n.  sp. 

Plate  LX,  figures  la-d.  i 

Determinative  characters. — Test  medium  in  size,  subovato  in  marginal  outline,  somewhat 
pointed  anteriorly  and  truncated  posteriorly;  the  whole  form  greatly  depressed,  being  thin  and 
nearly  flat  aroimd  a  narrow  marginal  area,  and  only  slightly  tumid  within  the  petaloidal  area ; 
under  sm-face  flat.  Ambulacral  petals  narrowlj^  elliptical,  the  posterior  pah-  extending  about 
half,  the  others  decidedly  more  than  half  way  to  the  margin.  Apex  and  apical  system  central, 
at  the  summit  of  the  tumid  area.  Peristome  small,  circular;  ambulacral  furrows  simple  and 
39800°— 15 0 


126  MESOZOIC   AXD   CEXOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

straight  for  about  half  the  distance  to  the  margin.  Periproct  very  small,  subcircular,  about 
one-fourth  the  way  from  the  posterior  margin  to  the  peristome. 

Dimensions. — -Length  40.5  millimeters;  width  39  millimeters;  height  5  millimeters. 

Description. — -Tliis  new  species  is  rare,  only  a  single  specimen  having  yet  been  discovered. 
As  this  specimen  was  found  in  South  Carolina,  the  form  is  named  in  honor  of  that  distmguished 
worker  upon  the  geology  and  paleontology  of  South  Carolina,  IVIr.  M.  Tuomey.  Tlie  test  is 
medium  in  size.  In  marginal  outline  it  is  subovate,  broadest  posteriorly,  narro^raig  until  some- 
what jjomted  anteriorly,  truncated  along  the  middle  of  the  posterior  border.  The  whole  form  is 
greatly  depressed,  being  quite  flat  all  around  the  area  outside  the  ambulacral  petals,  and  within 
the  petaloidal  area  rismg  only  slightly  to  form  a  very  low  broad  mound.  The  margin  of  the  test 
is  thin,  with  two  shallow  notches  opposite  the  ends  of  the  posterior  petals.  The  flattened  mar- 
ginal area,  from  the  ends  of  the  petals  to  the  edge,  is  thin  and  rather  narrow,  especially  ante- 
riorly, where  it  is  decidedly  less  wide  than  the  petals  are  long,  while  posteriorly  the  width  is 
about  equal  to  the  length  of  the  petals.  The  under  surface  is  flat  or  slightly  concave  from 
edge  to  edge.     The  apex  is  central  or  subcentral,  at  the  summit  of  the  tumid  area. 

The  ambulacral  areas  are  narrow  in  the  petaloid  region,  but  wide  at  the  margin,  where  they 
are  wider  than  the  inter  ambulacral  areas.  The  dorsal  portions  are  petaloid.  The  petals  are 
of  medium  size,  subequal  in  length,  narrowly  elliptical  in  form,  slightly  open  at  the  ends;  the 
posterior  pair  extending  about  half,  the  others  decidedly  more  than  half,  the  way  to  the  margin. 
The  poriferous  zones  are  rather  wide,  almost  as  wide  as  the  interporiferous  areas;  inner  row  of 
pores  oval,  the  outer  slitlike;  the  pairs  of  pores  conjugated.  A  few  pairs  of  pores  extend  beyond 
the  ends  of  the  petals. 

The  interambulacral  areas  are  rather  wide  between  the  petals,  wider  than  the  ambulacral 
areas;  of  nearly  unifoiTQ  width  to  the  margin  where  somewhat  narrower  than  the  ambulacral 
areas;  composed  of  large  polygonal  plates.  The  whole  surface  of  the  test  is  covered  with  small 
uniform  tubercles,  which  are  slightly  larger  on  the  under  side. 

Tlie  apical  system  is  central  or  subcentral;  coincident  with  the  apex.  The  details  are 
indistmct  upon  the  specimen;  but  the  madreporite  is  relatively  large,  flush  with  the  surface, 
with  five  genital  pores  near  its  edge. 

The  peristome  is  small,  circular  oi-  subcu'cular,  subcentral;  the  ambulacral  furrows  appar- 
ently simple  and  straight  for  about  half  the  distance  to  the  margin,  where  they  probably  fork 
symmetiically  though  they  do  not  show  well  on  the  only  specimen  found. 

The  periproct  is  very  small,  about  half  the  diameter  of  the  peristome,  subcircidar,  approach- 
ing an  inframarginal  position,  bemg  situated  on  the  under  surface  about  one-fourth  the  way  from 
the  posterior  margin  to  the  peristome. 

Belated  forms. — -This  species  is  very  similar  to  some  specimens  of  Periarchus  lyeUi,  but  differs 
from  it  in  bemg  more  pointed  anteriorly,  in  being  truncated  posteriorly,  and  in  having  its 
periproct  nearer  to  its  posterior  border.  S.  conradi  resembles  S.  tuomeyi,  but  can  be  separated 
by  its  smaller  size,  subquadrate  posterior  end,  emarginate  posterior  border,  and  nearer  approach 
of  periproct  to  posterior  border.  S.  tuomeyi  also  resembles  S.  mississippiensis  in  general 
appearance,  but  the  latter  is  readily  distinguished  by  the  submarginal  location  of  its  periproct. 
There  do  not  appear  to  be  any  foreign  forms  which  are  closely  related. 

Localitij. — -Fourteen  miles  south  of  Fort  Motte  station,  Orangeburg  County,  S.  C. 

Geologic  Jiorizon. — -Eocene,  probably  from  the  McBean  formation  of  the ' Claiborne  group, 
middle  Eocene.     Tlie  specimen  occurred  in  a  greensand  matrix. 

Collection. —  U.  S.  National  Museum  (137970). 

SCUTELLA   (?)   CONRADI    (Cottcau). 

Plate  LXn',  figures  la-d. 

non  Scutdla  niarginalis  DesmouUns,  1837,  Etudes  sur  les  ecliinides,  Tabl.  synon.,  p.  234. 
non  Laganum  marginalc,  Agassiz  and  Desor,  1847,  Cat.  raisonne  echinodermes,  vol.  7,  p.  133. 
non  Sismondia  marginalis  Desor,  1858,  Synopsis  des  ecliinides,  p.  226,  PI.  XXVII,  figs.  26-28. ' 
Sismondia  marginalis  Conrad,  ISG-'i,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  7.5,  no  fig. 
Mortonia  (Periarchus)  marginalis  Conrad,  1866,  Smithsonian  Misc.  Coll    vol.  7  (200),  p.  21. 


EOCENE   ECHINODEEMATA.  127 

Sismondia  conradi  Cotteau,  1891,  Paleontologie  franfaise,  Echinides  eocenes,  vol.  2,  p.  300. 
non  Sismondia  marginalis  Cotteau,  1891,  Paleontologie  franfaise,  Echinides  ^octoes,  vol.  2,  p.  267. 
Monostychia  marginalis  Gregory,  1891,  Geol.  Soc.  America  Bull.,  vol.  3,  p.  105. 
Periarchus  (?)  marginalis  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Determinative  characters. — Test  small  in  size;  marginal  outline  subquadrate  to  suboval,  the 
sides  and  posterior  margin  being  truncated  so  that  the  posterior  border  is  semiquadrate  and  the 
anterior  border  is  semicircidar;  the  whole  form  much  depressed,  though  centrally  it  rises  m  the 
form  of  a  low  gently  rounded  mound ;  margin  thin,  with  a  small  notch  in  the  middle  of  the  pos- 
terior edge;  inider  surface  flat.  Amljulacral  petals  elliptical,  extending  about  halfway  to  the 
margm.  Apex  and  apical  system  central,  or  slightly  excentric  anteriorly.  Peristome  small, 
subcircular ;  ambulacral  furrows  simple  and  straight  for  over  halfway  to  the  margin,  then  becom- 
ing obscure.     Periproct  very  small,  subpentagonal  or  subcircular,  inframarginal. 

Dimensions. — Length  21  millimeters;  width  21  millimeters;  height  .3  millimeters.  This  is 
Conrad's  type,  here  figured  for  the  first  time. 

Description. — The  species,  though  described  by  Conrad  in  1865,  has  never  been  figured  and 
is  not  very  well  known.  Tliere  is  some  doubt  in  regard  to  its  generic  position.  Gregory's  remark 
that  it  should  be  transferred  to  the  genus  Monostychia  is  not  agreed  to,  for  the  reason  that  the 
type  reveals  five  genital  pores  and  fails  to  show  any  continuation  of  the  actinal  grooves  abac- 
tinaUy.  The  test  is  small  in  size,  the  tj-pe  being  about  ^  inch  in  diameter  and  about  J  inch 
in  height.  In  marginal  outline  it  is  subquadrate  to  suboval,  with  the  sides  and  posterior  margin 
truncated  so  that  the  posterior  half  of  the  border  is  semicjuadrate  and  the  anterior  half  semi- 
circular. The  upper  surface  is  so  much  depressed  all  aromid  the  marginal  area  as  to  be  cjuite 
flat,  or  even  shghtly  concave,  but  within  the  area  covered  by  the  ambulacral  petals  it  rises  in  the 
form  of  a  low,  gently  rounded  mound  with  a  rather  broad,  flattened  summit.  The  margin  is  thin, 
though  shghtly  thicker  than  the  sul)marginal  area,  with  a  small  notch  in  the  middle  of  the  pos- 
terior side.  The  under  surface  is  flat.  The  apex  is  central  or  slightly  excentric  anteriorl}',  at 
the  summit  of  the  tumid  central  area. 

The  ambulacral  areas  are  narrow  in  the  petaloid  region,  wider  in  the  marginal  region;  but 
the  condition  of  the  specimen  does  not  permit  the  making  out  of  many  details.  The  dorsal  por- 
tions of  the  ambulacra  are  petaloid.  The  petals  are  subequal  in  length,  elliptical  in  form,  slightly 
open  at  the  ends  and  extend  about  halfway  to  the  margin.  The  poriferous  zones  are  rather  wide, 
but  slightly  less  so  than  the  interporiferous  areas;  the  inner  row  of  pores  oval,  the  outer  slitlike; 
the  pairs  of  pores  conjugated.     A  few  pairs  of  pores  occur  beyond  the  ends  of  the  petals. 

The  interambidacral  areas  are  relatively  large.  The  whole  surface  of  the  test  is  covered 
with  small  uniform  tubercles,  which  are  slightly  larger  on  the  under  side. 

The  apical  system  is  subcentral,  at  the  summit  of  the  central  mound.  The  madreporite  is 
relatively  large,  occupying  the  larger  part  of  the  area  covered  by  the  system,  and  faintly  tumid. 
There  are  five  genital  pores  near  the  edge  of  the  madreporite  and  five  small  radial  plates  each 
perforated  by  a  minute  pore. 

The  peristome  is  small,  subcircular,  central;  the  ambulacral  furrows  simple,  straight,  and 
quite  distinct  for  slightly  more  than  half  the  distance  to  the  margin,  then  becoming  obscure.  A 
small  ridge  extends  from  the  peristome  along  the  middle  of  each  ambulacral  furrow  for  a  greater 
distance  than  the  diameter  of  the  peristome. 

The  periproct  is  very  small,  considerably  smaller  than  the  peristome,  subpentagonal  or  sub- 
circ\dar,  situated  on  the  under  surface  near  the  posterior  margin,  being  about  one-fifth  the  radius 
from  the  border. 

Related  forms. — Of  American  forms  S.  (?)  conradi  most  closely  resembles  S.  tuomeyi  and  some 
of  the  smaller  specimens  of  Periarchus  lyelli,  but  is  easily  separated  from  these  species  by  its 
subquadrate  marginal  outline  and  the  inframarginal  position  of  its  periproct.  It  also  resembles 
S.  mississippiensis,  but  its  periproct  is  less  nearly  marginal.  It  does  not  appear  closely  related 
to  any  of  the  known  foreign  forms. 

Locality. — Conrad  said  his  type  came  from  near  Charleston,  S.  C. 

Geologic  horizon. — Probably  Cooper  marl,  upper  Eocene. 

Collection. — Academy  of  Natural  Sciences  of  Philadelphia  (1081). 


128  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA   OF   THE   UNITED   STATES. 

Genus  MORTONELLA  Pomel. 

non  Mortonia  Gray,  1851. 

Mortonia  Desor,  1857,  Synopsis  des  echinides  fossiles,  p.  231. 

MortoneUa  Pome],  1883,  Classif.  m^thodique  et  genera  des  echinides  vivants  et  fossiles,  p.  70. 

Mortonella  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  684. 

The  genus  Mortonella  as  used  here  includes  the  scutella-like  forms  having  a  central'or  sub- 
central  apical  system,  periproct  less  than  halfway  from  peristome  to  margm,  thick  margin,  fire 
genital  pores,  and  ambulacral  area  either  flat  or  tumid.  The  general  form  is  discoidal.  The 
ambulacral  furrows  are  simple  and  straight  for  halfway  to  the  margin,  then  bifurcate  and  proceed 
to  the  margin  without  much  further  branching.  The  ambulacral  petals  extend  sHghtly  more 
than  halfway  to  the  margin  and  are  open  at  the  ends.  The  chief  difference  between  Mortonella 
and  Periarchus  is  in  the  thickness  of  the  margin. 

Mortonella  quinquefakl^^  (Say). 
Plate  LX,  figures  2a-2f;  Plate  LXI,  figures  la-b. 

Scutellaquinq%iefaria  Sa,y,  1825,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.,  vol.  5,  p.  228,  no  fig. 

non  Sciitella  rogersi  Morton,  1834,  Synopsis  organic  remains  Cretaceous,  p.  77,  PI.  XIII,  fig.  3. 

non  Scuklla  rogersi  Desmoulins,  1837,  Etudes  sur  les  echinides,  Tabl.  sjTion.,  p.  236. 

non  Lagana  rogersi  Agassiz,  1840,  Cat.  syst.  ectyporum  echinodermatum  fossilium  musei  Neocomensis,  p.  6.  Merely 
listed  Morton's  form. 

Scutella  rogersi  Agassiz,  1841,  Hon.  echinodermes  vivans  et  fossUes,  vol.  2,  Des  scutelles,  pp.  85,  86,  PI.  XIX, 
figs.  1-4.     Described  and  figured  Say's  form  under  the  impression  that  he  was  dealing  with  Morton's. 

Scutella  rogersi  Agassiz  (pars),  1847,  Cat.  raisonne  echinodermes,  vol.  7,  p.  135. 

Scutella  rogersi  Bronn  (pars),  1848,  Index  pala?ontologicus,  vol.  1,  p.  1126;  vol.  2,  p.  196. 

Mortonia  rogersi  Desor  (pars),  1858,  Synopsis  des  ecliinides  fossiles,  p.  231,  no  fig.  Described  Say's  form  but  cited  Mor- 
ton's figure. 

Mortonia  rogersi  Dujardin  and  Hup6, 1862,  Hist.  nat.  des  zoophytes  echinodermes,  p.  563. 

Mortonia  rogersi  Conrad  (pars),  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  74. 

Mortonia  quinquefaria  (Say)  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  32. 

Scutella  rogersi  Quenstedt,  1872-1875,  Petrefact.  Deutschlands,  pt.  1,  vol.  1,  Echiniden,  pp.  525,  546. 

Mortonia  rogersi  Zittel,  1876-1880,  Handbuch  der  palaeontologie,  vol.  1,  pt.  1,  p.  522. 

Mortonia  rogersi  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  88. 

Mortonella  rogersi  Pomel,  1883,  Classif.  meth.  et  genera  des  echinides  A-ivants  et  fossiles,  Alger.,  p.  70. 

Scutella  mortoni  (Agassiz)  Quenstedt,  1885,  Handbuch  der  Petrefactenkunde,  p.  696. 

Scutella  ( Mortonia)  rogersi  De  Gregorio  (pars),  1890,  Mon.  faune  eocenique  Alabama,  p.  250,  PI.  XLIII,  figs.  16-20. 

Mortonia  quinquefaria  Gregory,  1891  (discussion),  Geol.  Soc.  America  Bull.,  vol.  3,  p.  105. 

Echinanlhus  quinquefaria  Gregory,  1891  (tabulation),  Geol.  Soc.  America  Bull.,  vol.  3,  p.  105.  This  was  evidently  a 
lapsus  calami. 

Scutella  rogersi  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  263. 

non  Mortonia  rogersi  Dana,  1895,  Manual  of  geology,  4th  ed.,  p.  898,  fig.  1491. 

Mortonella  rogersi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  685. 

Determinative  characters. — Test  of  medium  size;  discoidal;  circular  to  broadly  subovate  in 
marginal  outhne;  much  depressed,  upper  surface  more  or  less  tumid  centrally,  margin  and  sub- 
marginal  area  thick;  under  surface  flat.  Ambulacral  petals  large,  broad,  spatulate,  extending 
nearly  two-thirds  of  the  distance  to  the  margin.  Apex  and  apical  system  subcentral.  Peri- 
stome small,  circular;  ambulacral  furrows  simple  and  straight  nearly  halfway  to  the  margin, 
then  forking  symmetricaUy.  Periproct  very  small,  circular,  about  half  the  distance  from  peri- 
stome to  posterior  margin. 

Dimensions. — Specimen  A:  Length  56  millimeters;  width  58  milhmeters;  height  14  milU- 
meters.     Specimen  B:  Length  59  miUimeters;  width  61  milHmeters;  height  8  milhmeters. 

Description. — This  species  was  one  of  the  earhest  Cenozoic  forms  reported  from  American 
deposits.  It  was  first  described  by  Thomas  Say  in  1825.  Two  specimens,  which  are  probably 
Say's  types,  were  foxmd  by  the  writer  in  the  collection  of  the  Academy  of  Natural  Sciences  of 
Philadelphia.  This  species  has  been  of  ten  confused  with  Clypeaster  rogersi  (Norton),  owingpartly 
to  a  superficial  resemblance,  but  more  to  the  mistakes  of  L.  Agassiz  and  Desor.  Agassiz  was  the 
fibrst  to  figure  Say's  form;  but  unfortunately  having  figured  and  described  what  was  in  reahty 


EOCENE   ECHINODEKMATA.  129 

Say's  Scutella  quinquefaria  he  applied  to  the  form  Morton's  name  Scutella  rogersi.  The  forms 
themselves  are  perfectly  distinct,  even  belonging  to  different  families,  Say's  form  being  one  of 
the  Scutillidse  and  Morton's  one  of  the  Clypeastridse ;  but,  owing  to  the  mistakes  mentioned 
great  confusion  exists  in  regard  to  them  in  the  various  coUections  and  in  the  literature.  The 
separation  of  the  two  forms  is  not  at  all  difficult,  Clypeaster  rogersi  (Morton)  bemg  easily  distin- 
guished bj^  its  straight  unbranched  ambulacral  furrows,  its  more  concave  under  surface,  its  more 
tumid  ambulacral  petals,  its  less  circular  and  more  pentagonal  marginal  outline,  and  the  location 
of  its  periproct  nearer  the  posterior  border. 

This  species  is  also  interesting  because  on  it  Desor  founded  his  genus  Mortonia,  based  cliiefly 
upon  the  unusualty  thick  margin  for  a  Scutella-hke  form.  The  name  Mortonia  was  changed  by 
Pomel  to  Mortonella  because  Gray  had  appUed  the  name  Mortonia  to  a  different  genus  prior  to 
Desor's  use  of  it  for  the  present  genus. 

The  test  of  the  present  species  is  notably  discoidal  in  form.  It  is  of  medium  size,  the  dimen- 
sions varying  but  shghtly  from  those  already  given.  In  most  specimens  it  is  usually  circular  in 
marginal  outline,  though  in  some  it  is  broader  posteriorly  than  anteriorly.  The  whole  form  is 
much  depressed,  the  upper  surface  being  either  nearly  flat  or  having  a  low,  gently  rounded  cen- 
tral mound  involving  only  about  half  of  the  region  covered  by  the  ambulacral  petals.  The  vari- 
ations in  marginal  outline  and  tumidity  of  the  upper  surface  seem  almost  of  specific  value, 
but  intermediate  forms  show  a  gradation  from  one  to  the  other,  and  the  variation  in 
the  character  of  the  upper  surface  occurs  in  both  the  forms  which  are  circular  in  marginal 
outUne  and  those  which  are  broader  posteriorly.  The  region  involving  the  outer  part  of  each 
petal  is  faintly  concave.  The  margin  and  submarginal  area  are  thick,  usually  almost  as  thick  as 
the  average  thickness  of  the  test ;  the  margin  being  shghtly  thimier  and  less  roimded  posteriorly 
than  anteriorly,  faintly  undulating.  The  under  surface  is  flat  or  broadly  and  faintly  concave. 
The  apex  is  subcentral,  or  shghtly  cxcentric  anteriorlj^,  at  the  summit  of  the  more  or  less  tumid 
central  area. 

The  ambulacra  are  relatively  wide  in  the  petaloidal  region,  broader  in  the  marginal  region 
where  they  about  equal  the  interambidacral  areas.  The  dorsal  portions  are  petaloid;  the  petals 
large,  broad,  subequal  in  length,  the  odd  petal  being  shghtly  longer  than  the  rest,  spatulate  in 
form,  open  at  the  ends  and  extending  nearly  two-tliirds  the  cUstance  from  the  center  to  margin. 
The  poriferous  zones  are  very  wide,  wider  than  the  interporiferous  areas;  the  inner  row  of  pores 
nearly  straight  and  composed  of  oval  openings,  the  outer  row  shthke;  the  pairs  of  pores 
conjugated. 

The  interambulacra  are  relatively  narrow  in  the  petaloidal  region,  wide  in  the  marginal 
region,  where  about  equal  to  the  ambulacral  areas,  composed  of  large  polygonal  plates.  The 
whole  surface  of  the  test,  including  the  margins,  is  covered  with  small  uniform  tubercles  which 
are  shghtly  larger  on  the  under  side. 

The  apical  system  is  subcentral  or  shghtly  excentric  anteriorly  at  the  summit  of  the  test. 
The  madreporite  is  relatively  large,  occupying  the  larger  part  of  the  area  covered  by  the  system 
and  flush  with  the  surface.  There  are  five  large  genital  pores  near  the  edge  of  the  madreporite 
and  five  small  radial  plates  each  perforated  by  a  small  pore. 

The  peristome  is  small,  circular,  central,  the  ambidacral  furrows  simple  and  straight  nearly 
half  the  distance  to  the  margin,  then  forking  symmetrically,  each  pair  of  branches  continuing 
almost  to  the  margin.  Each  branch  gives  off  on  the  outside  one  side  branch  at  right  angles  about 
a  fourth  of  the  racUus  from  the  margin,  which  side  branches  soon  bend  and  in  turn  approach  the 
margin.  A  small  ridge  extends  along  the  middle  of  each  ambulacral  furrow  from  the  peristome 
to  the  fork  in  the  furrow. 

The  periproct  is  very  small,  circular,  situated  on  the  under  surface  about  half  the  way  from 
the  peristome  to  the  posterior  margin. 

Relatedforms. — The  thick  margin  and  discoidal  form  of  Mortonella  qumquefaria  afford  a  ready 
means  of  separating  it  from  most  American  echinoids.  Dendraster  perrini  is  similar  in  having 
a  thick  margin  but  differs  in  having  its  apical  system  posteriorly  excentric,  its  ambulacral 


130  MESOZOIC    AND   CENOZOIC    ECHINODEKMATA   OF    THE    UNITED    STATES. 

petals  relatively  longer  and  wider  open  at  the  ends,  and  its  periproct  inframarginal.  Peri- 
archus  lyelli  also  resembles  M.  quinquefaria  in  general  but  has  a  thin  margin.  Of  foreign  forms 
Scutellafaujasi  De  France  from  the  middle  Tertiary  of  France  is  closely  related  to  this  species. 
The  specimen  S.  faujasi  figured  by  Bronn  in  Lethsea  geognostica,  Plate  XXXVI,  figure  S, 
shows  the  tliick  margin,  discoidal  outline,  and  similarly  branching  ambulacral  furrows. 

Localities. — Near  MilledgeviUe  (Say's  types);  1  mile  southwest  of  Sandersville  (figured 
specimen  A);  Washington  County  (figured  specimen  B);  li  miles  northeast  of  Ten\'iUe;  Nor- 
ton; and  2  J  miles  south  of  Warthen,  Washington  County,  Ga. 

Geologic  Jiorizon. — Claiborne  group,  middle  Eocene,  and  Jackson  formation,  ( ?)  upper 
Eocene. 

Collections. — U.  S.  National  Museum  (9500,  A);  Academy  of  Natural  Sciences  of  Phila- 
delphia: Wagner  Free  Institute  of  Science;  Geological  Survey  of  Georgia;  Amherst  College  (B). 

Genus  PEBIABCHUS  Conrad. 

Periarchus  Conrad,  1866  (subgenus),  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  21. 
Periarchus  Grabau  and  Shimer,  1910,  North  Am.  index  fossils,  vol.  2,  p.  591. 
Periarchus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  687. 

The  genus  Periarchus  as  used  here  includes  the  Scutella-hke  forms  with  central  or  sub- 
central  apical  system,  periproct  actinal,  but  less  than  three-fifths  of  the  way  from  the  peristome 
to  the  margm,  thhi  margm,  five  genital  pores  and  more  or  less  abruptly  tumid  ambulacral  area. 
The  ambulacral  furrows  are  usually  sunple  and  straight  about  halfway  to  the  margin,  then 
bifurcate  and  proceed  to  the  margin  mthout  much  further  branching.  The  ambulacral  petals 
are  usually  short,  rarely  extending  more  than  halfway  to  the  margm,  more  or  less  open  at  the  ends. 

Periarchus  altus  Conrad. 

Plate  LVIII,  figures  la-e. 

Scutella  .sp.  Emmons,  1858,  Agriculture  Eastern  Counties:  North  Carolina  Geol.  Survey  Kept.,  p.  308,  figs.  247,  248. 

Sis7nondia  aha  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  pp.  74,  75,  no  figure. 

Mortonia  (Penarchiis)  alius  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  21. 

Mortonia  (Periarchus)  alius  Heilprin,  1884,  Contr.  Tertiary  geology  U.  S.,  p.  17. 

Sismondia  alta  Cotteau,  1889-1894,  Pal^ontologie  franfaise,  Echinides  eocenes,  vol.  2,  p.  300. 

Periarchus  altus  Gregory,  1891,  Geol.  Soc.  America  Bull.,  vol.  3,  p.  105. 

Periarchus  alius  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  699. 

Periarchus  sp.  6  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  699. 

Determinative  cliaracters. — Test  of  medium  size,  circular  m  margmal  outline,  much  depressed, 
less  so  centrally  where  it  rises  in  a  relatively  high,  broad,  obliquelj-  flattened  mound,  whose  apex 
is  noticeably  excentric  anteriorly;  margin  of  sides  and  posterior  end  thin,  anteriorly  the  upper 
sm-face  declmes  in  a  straight  line  from  apex  to  edge;  mider  surface  flat.  Ambulacral  petals 
subeUiptical,  relatively  large,  extending  about  halfway  to  the  margin.  Apical  system  slightly  ex- 
centric  posteriorly,  and  well  to  the  rear  of  the  apex.  Peristome  small,  circular,  slightly  excentric 
posteriorly;  ambrdacral  fuiTows  sunple  and  straight  for  slightly  more  than  half  the  way  to  the 
margin,  then  forking  symmetrically.  Periproct  very  small,  subcircular,  about  two-fifths  the 
way  from  the  peristome  to  the  posterior  border. 

Dimensions. — Length  57.5  milluneters;  width  59  millimeters;  height  12  mdlimoters.  This 
is  the  type,  refigurod. 

Description. — This  species  was  figured  and  partly  described  by  Emmons  as  early  as  1 S5S.  He 
placed  it  in  the  genus  ScuteUa  but  did  not  give  the  form  a  specific  name.  In  1S65  Conrad,  who  had 
seen  Emmons's  type,  gave  a  good  description  of  it  and  applied  the  appropriate  specific  name 
alta  but  he  did  not  figure  it.  It  is  rare,  only  the  one  specimen  fomid  by  Emmons  having  yet 
been  reported.  The  test  is  of  medium  size.  The  marginal  outline  is  circular.  The  upper  sur- 
face rises  centrally  in  the  form  of  a  low  broad  momid,  whose  apex  is  noticeably  forward  of  the 
center;  anteriorly  the  surface  declines  in  a  straight  line  from  the  apex  to  the  edge;  along  the 
posterior  margin  it  is  greatly  depressed  and  nearlv  flat  from  the  edge  to  the  petaloid  region,  then 
rises  at  first  rather  steeply  then  more  gently  to  the  apex.     The  relative  height  of  the  central 


EOCENE   ECHINODEEMATA.  131 

mound  is  greater  than  m  most  fornas  likely  to  be  confused  with  it,  being  more  than  one-fifth  of 
the  diameter  of  the  test.  The  margin  of  the  sides  and  posterior  end  is  thm.  The  imder  surface 
is  flat,  or  faintly  concave  between  the  margin  and  the  region  around  the  peristome.  The  apex 
is  noticeably  excentric  anteriorly  at  the  summit  of  the  tumid  area. 

The  ambulacral  areas  are  relatively  wide  in  the  petaloid  region  though  ^vider  m  the  mar- 
guial  region,  in  both  cases  being  ■\\-ider  than  the  interarabulacral  areas.  The  dorsal  portions  of 
the  ambulacra  are  petaloid.  The  petals  are  relatively  large  and  broad;  subequal  ui  length,  the 
posterior  pan-  bemg  slightly  shorter  than  the  rest;  subelliptical  m  form;  slightly  open  at  the 
ends;  extending  slightlj-  more  than  halfway  to  the  marghi.  The  poriferous  zones  are  rather 
wide,  but  less  so  than  the  wide  mt;^rporiferous  areas ;  the  mner  row  of  pores  oval,  outer  row  slit- 
like; paii-s  of  pores  conjugated.     A  few  pau-s  of  pores  occur  beyond  the  ends  of  the  petals. 

The  mterambulacral  areas  are  relatively  small  between  the  petals  and  though  wide  near  the 
margm  m  both  cases  are  smaller  than  the  ambulacral  areas;  composed  of  large  polygonal  plates. 
The  whole  surface  of  the  test  is  covered  with,  small  uniform  tubercles,  which  are  slightly  larger 
on  the  under  side. 

The  apical  system  is  slightly  excentric  posteriorly,  located  well  back  of  the  apex  on  a  flat- 
tened area  which  extends  obUquely  downward  and  backward  from  the  apex  and  is  about  tlireo 
times  the  diameter  of  the  system.  The  madreporite  is  relativclj-  large,  occupymg  the  larger 
part  of  the  area  covered  by  the  system,  subpentagonal,  flush  with  the  surface.  There  are  five 
large  circular  genital  pores  perforating  the  basal  plates  at  the  points  of  the  madreporic  pentagon, 
and  five  small  radial  plates,  each  perforated  by  a  minute  pore. 

The  peristome  is  small,  circular,  slightly  excentric  posteriorly;  the  ambulacral  furrows 
simple  and  straight  for  slightly  more  than  half  the  distance  to  the  margui,  then  forkbig  symmet- 
rically, and  at  rather  a  -w-ide  angle,  each  pan-  of  branches  contmumg  nearly  to  the  margui.  A 
small  ridge  extends  out  for  a  short  distance  from  the  peristome  along  the  middle  of  each  ambida- 
cral  furrow. 

The  periproct  is  very  small,  subcu'cular,  situated  on  the  under  surface  about  two-fifths 
of  the  way  from  the  peristome  to  the  posterior  border.  It  is  nearer  the  peristeme  than  are 
the  forks  m  the  ambulacral  furrows. 

Belated  forms. — The  species  is  most  closely  related  to  P.  lyelli,  from  which,  however,  it  is 
easily  distinguished  bj^  its  anteriorly  excentric  apex,  by  the  noncoincidence  of  its  apical  system 
and  apex,  by  the  fact  that  the  central  tumid  mound  involves  nearly  the  whole  upper  surface 
instead  of  bemg  confhietl  to  the  petaloid  region,  and  by  its  broader  petals.  No  foreign  forms 
appear  to  be  closely  related  to  this  species. 

Locality. — Core  Creek,  Craven  County,  N.  C. 

Geologic  horizon. — Trent  marl,  middle  Eocene. 

Collection. — Williams  College. 

Peeiarchus  lyelli  Conrad. 

Plate  LXI,  figures  2a-f ;  Plate  LXII,  figures  la-c,  2a-d. 

Scutella  lyelli  Conrad,  1834,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.,  vol.  7,  p.  152,  no  figure. 

IScuteUa  lyelli  Morton,  1834,  Sj-nopsis  organic  remains  Cretaceous,  p.  77,  PI.  X,  fig.  8.     Figure  shows  upper  surface 

only;  no  description. 
Scutella  lyelli  Conrad,  1842,  Nat.  Inst.  Promotion  Sci.  Proc,  2d  Bull.,  p.  175. 

ISculella  lyelli  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  1126;  vol.  2,  p.  196.     Based  on  Morton. 
ISisnondia  lyelli  Desor,  1858,  SjTiopsis  des  e,;'hinides,  p.  227.     Based  on  ilorton. 

non  Scutella  lyelli  Emmons,  1858,  Agriculture  Eastern  Counties,  North  Carolina  Cieol.  Survey  Rept.,  p.  308,  text  fig.  246. 
ISculella  hjdli  Gabb,  1S53,  Cat.  invert,  fossils  Cretaceous,  p.  19.     Bassd  on  Morton. 
^Scutella  lyelli  Dujardin  and  Hupe,  1862,  Hist.  nat.  zoophytes  ecliinodermes,  p.  559.     Based  on  Morton. 
Sismondia  lyelli  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelpliia  Proc,  p.  74. 
Mortonia  (Periarchus)  lyelli  Conrad,  1866,  Smithsoni.xn  Misc.  Coll.,  vol.  7  (200),  p.  21. 
?Scutella  lyelli  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  89.     Based  on  Morton, 
non  Scutella  lyelli  Heilprin,  1884,  Contrib.  tertiary  geology  U.  S.  p.  17. 
Scutella  lyelli  Smith  and  .lolinson,  1887,  U.  S.  Geol.  Survey  Bull.  43,  p.  21. 
^Sismondia  lyelli  Cotteau,  1889-1894,  Pal^ontologie  frangaise,  Echinides  ^ocfenes,  vol.  2,  p.  301.     Based  on   Morton. 


132  MESOZOIC    AND    CENOZOIC   ECHINODEEMATA    OP    THE    UNITED    STATES.  ' 

Scuiella  lyelli  De  Gregorio,  1S90  (pars),  Mon.  faune  eoc^nique  Alabama,   pp.  25(>-2.51,  PI.  XLIII,  fig.  21.     Conrad's 

description  but  ^Morton 's  figure. 
ScuieUa  lyelli  Clark,  1891,  Jolms  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
IScutella  lyelli  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  263.     Based  on  Morton. 
Periarchus  sp.  a.  Stefanini,  1911,  Soe.  geol.  italiana  Boll.,  vol.  30,  p.  696. 
"fSismondia  (?)  lyelli  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Determinative  characters. — Test  variable  in  size,  subcirciilar  to  snbovate  in  marginal  outline; 
much  depressed,  less  so  centrally  where  it  rises  in  a  gently  rounded,  convex  mound  of  variable 
height;  margin  and  wide  submarginul  area  thin;  under  surface  flat.  Ambulacral  petals  sub- 
elliptical  to  suboblong,  extending  about  half  way  to  the  margin.  Apex  and  apical  system  central 
or  subcentral,  on  the  somewhat  flattened  summit  of  the  tumid  area.  Peristome  small,  subcir- 
cular;  ambulacral  furrows  simple  and  straight  for  about  half  way  to  the  margin,  then  forking 
symmetrically.  Periproct  very  small,  subcircular,  from  one-third  to  slightly  more  than  halfway 
from  peristome  to  posterior  border. 

Dimensions. — -Specimen  A:  Length  90  millimeters;  width  90  millimeters;  height  12  milli- 
meters. Specimen  B :  Length  32  millimeters;  width  31  millimeters;  height  6  millimeters.  Speci- 
men C:  Length  35  millimeters  ;  width  34  millimeters;  height  5  millimeters. 

Description. — Considerable  confusion  exists  in  regard  to  this  and  allied  forms  in  the  various 
collections  and  in  the  literature.  Conrad  as  early  as  1834  gave  an  excellent  description  of  the 
species  but  no  figure.  The  same  year  Morton  published  a  poor  upper  view  only  of  a  small  form 
which  he  called  Scufella  hjelU  Conrad,  but  gave  no  description.  Conrad's  form  was  a  large 
specimen  from  Alabama,  forms  similar  to  which  have  easily  been  identified  among  the  material 
studied  by  the  writer.  Morton's  specimen  was  a  small  one,  whose  present  whereabouts  is 
unkno\vn,  and  was  from  a  locality  which  is  uncertain.  Desor,  Cotteau,  and  others,  basing  their 
action  upon  Morton's  figure,  have  placed  the  species  lyelli  in  the  genus  Sismondia.  This  is  an 
error,  as  Conrad's  form  has  all  the  characters  of  Periarchus.  Unless  his  figured  specimen  is  dis- 
covered, Morton's  form  must  remain  of  doubtful  character  and  is  therefore  placed  among  the 
doubtful  and  unrecognized  species. 

Periarchus  lyelli  is  one  of  the  most  abundant  of  the  American  Cenozoic  forms,  at  times  occur- 
ring in  such  numbers  and  with  such  constancy  as  to  afford  a  valuable  aid  in  determining  the 
geologic  horizon  in  which  it  is  found.  The  test  is  variable  in  size,  ranging  from  1  to  3^  inches  in 
diameter.  In  marginal  outline  it  is  circular  or  subcircular  to  subovate,  some  specimens  slightly 
others  decidedly  broader  posteriorly  than  anteriorly.  All  around  the  area  outside  the  ambulacral 
petals  it  is  greatly  depressed  and  quite  flat;  but  within  the  petaloidal  area  it  rises  in  the  form  of  a 
gently  rounded  mound  with  more  or  less  flattened  summit,  which  ranges  from  ^  to  ^  inch  in  height 
according  to  the  size  and  age  of  the  specimen.  Sometimes  the  mound  approaches  a  subcorneal 
form,  but  even  then  the  sides  are  more  or  less  convex.  The  margin  of  the  test  is  thin  and  slightly 
undulating,  both  characters  being  most  pronounced  posteriorly;  usually  there  are  broad  shallow 
notches  opposite  the  ends  of  the  posterior  petals,  though  these  may  be  inconspicuous  or  absent 
in  the  smaller  specimens.  The  flattened  marginal  area,  from  the  ends  of  the  petals  to  the  edge, 
is  thin  and  wide,  being  about  as  wide  as,  or  wider  than  the  petals  are  long,  and  usually  widest 
posteriorly.  The  under  surface  is  flat  or  nearly  so  with  a  broad  faintly  depressed  ring  about 
midway  between  margin  and  peristome.  The  apex  is  central  or  slightly  excentric  anteriorly,  at 
the  summit  of  the  tumid  area. 

The  ambulacral  areas  are  narrow  in  the  petaloid  region  but  wide  at  the  margm  where  they 
about  equal  the  interambulacral  areas.  The  dorsal  portions  are  petaloid.  The  petals  are  of 
medium  size;  subecjual  in  length,  the  odd  petal  being  slightly  longer  than  the  rest;  subelliptical 
to  elongate  elliptical  or  suboblong  in  form;  slightly  open  at  the  ends;  extending  half  or  slightly 
more  or  less  than  half  the  way  to  the  margin.  The  poriferous  zones  are  rather  wide,  almost  as 
wide  as  the  interporiferous  areas;  inner  rows  of  pores  nearly  straight  and  parallel  and  formed  of 
oval  pores,  outer  rows  of  pores  slitlike;  pairs  of  pores  conjugated.  A  few  pairs  of  pores  occur 
beyond  the  ends  of  the  petals. 

The  interambulacral  areas  are  large,  relatively  wde  between  the  petals  (usually  wider 
than  the  ambulacral  areas),  nearly  uniform,  and  composed  of  large  polygonal  plates.     The 


EOCENE    ECHINODEKMATA.  133 

whole  surface  of  the  test  is  covered  with  small  uniform  tubercles  which  are  slightly  larger  on 
the  under  side. 

The  apical  system  is  central  or  slightly  excentric  anteriorly,  on  the  somewhat  flattened  sum- 
mit of  the  central  mound.  The  madreporite  is  relatively  large,  occupying  the  larger  part  of  the 
area  covered  by  the  system  and  flush  with  the  surface.  There  are  five  genital  pores  near  the 
edge  of  the  madreporite  and  five  small  radial  plates  each  perforated  by  a  small  elliptical  pore. 

The  peristome  is  small,  subcircular,  central  or  slightly  excentric  anteriorly;  the  ambulacral 
furrows  simple  and  straight  for  from  one  to  two-thirds  the  distance  to  the  margin,  then  forking 
symmetrically  at  an  angle  usually  of  about  45°,  each  pair  of  branches  continuing  almost  to  the 
margin.  On  well-preserved  specimens,  each  branch  may  be  seen  to  give  off  on  the  outside  one 
important  side  branch  at  right  angles  about  halfway  between  the  fork  and  the  margin,  which  side 
branches  soon  bend  and  in  turn  approach  the  margin.  A  small  ridge  extends  out  from  the 
peristome  for  a  short  distance  along  each  ambulacral  furrow. 

The  periproct  is  very  small,  about  half  the  diameter  of  the  peristome,  circular  or  subcii'cular, 
situated  on  the  under  surface  from  one-third  to  slightly  more  than  one-half  the  way  from  the 
peristome  to  the  posterior  border. 

Related  forms. — This  species  presents  so  many  variable  features  that  several  apparently  dis- 
tmct  varieties  of  it  might  have  been  recognized  and  separately  described — such  as  one  with  a 
transversely  elongate  subtriangular  marginal  outhiie,  or  one  with  pcrijiroct  midway  between 
margin  and  peristome — but  in  each  case  intermediate  forms  show  a  gradation  between  the 
possible  variety  and  typical  representatives  of  the  species.  P.  lyeUi  Com-ad  is  closely  related 
to  the  American  forms  P.  pileus-sinensis  and  P.  protuberans,  both  of  which,  however,  have  a 
relatively  higher  and  more  conical  central  tumid  area.  P.  protuberans  is  further  distinguished 
by  its  characteristic  swollen  anterior  interporiferous  area  and  smaller  petaloid  area.  P.  lyelli 
also  greatly  resembles  S.  tuomeyi  which,  however,  differs  m  being  somewhat  truncated  posteri- 
orly and  in  having  its  periproct  nearer  the  posterior  border.  In  superficial  characters  P.  lyelli 
greatly  resembles  S.  mississippiensis,  but  the  latter  is  easily  separated  by  the  inframarginal 
position  of  its  peripi'oct.     It  does  not  appear  to  be  closely  related  to  any  of  the  foreign  forms. 

Localities. — Near  Claiborne  (Conrad's  type  and  our  specunen  A);  Cedar  Creek,  Clarke 
County;  St.  Stephens,  near  Cocoa,  Choctaw  Coimty;  and  Clarksville,  Ala.;  Shubuta  Creek, 
21  miles  north  of  Shubuta;  Chickasawhay  Eiver,  near  Shubuta;  and  Shell  Prairie,  near  Pachuta, 
Miss.;  14  miles  below  Macon,  Twiggs  County,  Ga.;  Mount  Enterprise,  Rusk  County,  and  2 
miles  east  of  Alto,  Clierokee  County,  Tex.;  Castle  Hayne  (specimen  B);  City  Rock  Quarry, 
Smith  Creek;  and  Rocky  Pomt,  near  Wilmuigton,  N.  C. 

Geologic  horizo7i. — Claiborne  group  (middle  Eocene)  and  Jackson  formation  (upper  Eocene) . 
In  Texas  in  the  "marme  substage"  of  the  Claiborne.  In  Mississippi  probably  near  the  base  of 
the  Lisbon  marl.  In  Alabama  abundant  in  the  Scutella  zone  at  the  base  of  the  Jackson,  "just 
above  the  Claiborne  fossiliferous  sand."  In  North  Carolma,  m  the  Castle  Hayne  limestone 
(upper  Eocene  or  Oligocene). 

Collections. — Boston  Society  of  Natural  History  (larger  figured  form)  (1553,  A);  U.  S. 
National  Mxiseum  (smaller  figured  fonu);  Alabama  Geological  Survey;  American  Museum  of 
Natural  History ;  Wagner  Free  Institute  of  Science ;  Williams  College ;  Amherst  College ;  Johns 
Hopkins  University  (T  2003,  B;  T  2004,  C). 

Periarchus  protuberans  Twitchell,  n.  sp. 

Plate  LXII,  figures  3a-f. 

Determinative  characters. — Test  of  medium  size,  subcircular  in  marginal  outlme;  much 
depressed,  less  so  centrally  where  it  rises  m  a  high,  slightly  asymmetric  cone;  margm  very 
thui,  broadly  dentate  posteriorly;  under  surface  flat.  Ambulacral  petals  elliptical,  very  small, 
extending  about  one-third  the  distance  from  center  to  margm.  The  anterior  interporiferous 
area  swollen  near  the  apical  system  which  k  slightly  excentric  posteriorly  and  inclined  down- 
ward and  backward  from  the  subcentral  apex.  Peristome  very  small,  circular,  in  a  slight  con- 
cavity; ambulacral  furrows  simple  and  straight  for  about  half  way  tc  the  margin,  then  forking 


134  MESOZOIC   AND    CENOZOIC    ECHINODEKMATA    OF    THE    UNITED    STATES. 

symmetrically.  Periproct  very  small,  oval  or  subovate,  on  the  under  surface  about  one-fourth 
the  distance  from  the  peristome  to  the  posterior  margin. 

Dimensions. — Length  54  milliiueters;  width  53  millimeters;  lieight  9  millureters. 

Description. — This  new  species  is  one  of  the  handsomest  of  American  scutellid  forms.  It 
is  very  delicate  and  fragile  and  so  thui  that  it  is  translucent  from  the  edge  halhvay  to  the  center. 
It  is  a  rare  form,  not  over  half  a  dozen  individuals  having  been  reported,  all  of  which  are  from 
the  Eocene  deposits  of  Mississippi,  where  it  occui-s  in  association  with  P.  jnleus-sinensis  and 
P.  lyelli.  Tlie  test  is  of  medium  size,  ranging  fi'oni  li  to  2i  inches  in  diameter;  and  subchcular 
ui  marguial  outline.  All  around  the  area  from  the  edge  nearly  to  the  petals  it  is  greatly  depressed 
and  nearly  flat;  but  within  and  slightly  beyond  the  petaloidal  area  it  rises  in  the  form  of  a  high, 
sliglitly  unsymmetrical  cone  Mliich  varies  in  height  from  |  to  h  an  inch.  The  margm  of  the  test 
is  very  thin  all  around,  almost  like  a  knife  edge,  and  is  decidedly  undulating,  or  zigzag,  especially 
posteriorly,  where  it  is  broadly  dentate.  Tlie  under  surface,  though  for  the  most  part  flat,  is 
slightly  and  broadly  concave  around  the  margm  and  the  peristome.  The  apex  is  subcentral 
at  the  summit  of  the  central  cone. 

The  ambulacral  areas  are  narrow  in  the  jjetaloid  region  but  wide  in  the  marginal  region 
where  they  about  ecpial  the  interambulacral  areas.  The  doi-sal  jjortions  are  petaloid.  Tlae 
petals  are  subecjual  in  length,  the  odd  petal  slightly  longer  than  the  rest;  relatively  quite  small, 
extending  only  about  two-fifths  the  distance  from  center  to  margin,  the  total  area  covered  by 
the  petals  being  noticeabh'  less  than  in  most  similar  forms.  The  jietals  are  elli|)tical  in  form 
and  nearly  closed  at  the  ends;  the  poriferous  zones  rather  wide  though  less  so  than  the  inter- 
poriferous  areas,  widest  at  their  distal  ends;  the  mner  row  of  pores  oA'al,  outer  row  slitlike;  the 
pah's  of  pores  conjugated.  The  anterior  mterporiferous  area  is  swollen  near  the  apical  region 
so  as  to  foi-m  a  small,  narrow  protuberance,  confined  withm  the  mterporiferous  area,  largest 
nearest  the  apical  system  and  constituting  the  apex  of  the  test.  This  protuberance  is  one  of 
the  most  striking  and  most  distinctiA^e  features  of  the  form;  and  suggested  the  specific  name. 

Tlie  interambulacral  areas  are  large,  nearly  uniform,  and  composed  of  large  polygonal 
plates.  The  whole  surface  of  the  test  is  covered  with  small  uniform  tubercles  which  are  slightlj' 
larger  on  the  under  side. 

The  apical  system  is  slightly  excentric  posteriorly,  inclined  downward  and  backward  from 
the  swollen  anterior  mtei'poriferous  area,  on  the  steep  posterior  slope  of  the  central  subconical 
mound.  The  madreporite  is  relatively  large,  occupying  the  lai-ger  part  of  the  area  covered  by 
the  system.  There  are  five  genital  pores  near  the  edge  of  the  madreporite,  and  five. small  radial 
plates,  each  perforated  by  a  small  ellijitical  pore. 

The  peristome  is  very  small,  not  much  larger  than  the  periproct,  circular,  central,  in  a  slight 
concavity;  ambulacral  furrows  simple  and  straight  for  about  one-half  the  distance  from  peris- 
tome to  margm,  then  forkmg  symmetrically,  each  pau  of  branches  continuing  nearly  to  the 
margin  and  each  branch  giving  ofl^  one  important  side  branch  at  right  angles  at  one-thu'd  to  one- 
fourth  radius  length  from  the  margin ;  these  side  branches  soon  bend  and  in  turn  approach  the 
margin.     A  small  ridge  extends  for  a  short  distance  along  the  middle  of  each  ambulacral  furrow. 

The  periproct  is  very  small,  oval  or  suboA-ate  m  outlme,  the  round  end  being  nearest  the 
peristome,  on  the  under  surface  from  one-fourth  to  one-third  the  distance  from  ^jeristome  to  the 
posterior  margm.     It  is  much  nearer  the  peristome  than  are  the  forks  in  the  ambulacral  furroAvs. 

Related  forms. — P.  protuberant  is  A'^ery  shnilar  in  aj^pearance  to  P.  pileus-sineiisis  (RaA'enel), 
resembling  it  more  closely  than  it  does  any  other  American  form.  It  is,  lioweA^er,  readily  dis- 
tmguished  by  its  protuberant  anterior  interporiferous  area,  smaller  petaloidal  area,  the  position 
of  its  apical  system  to  the  rear  oi  the  apex,  its  thmner  marginal  area,  smaller  peristome,  and  the 
nearer  approach  of  its  periproct  to  the  peristome.  No  foreign  forms  apjiear  to  be  closely  related 
to  this  species. 

Localities. — Shubuta  Creek,  2^  miles  north  of  Shubuta  (type),  and  C'hickasaAvhay  RiA^er. 
Shubuta,  Miss. 

Geologic  horizon. — Jackson  formation,  upper  Eocene. 

Collection.— V .  S.  National  Museum  (1646S5). 


EOCENE   ECHINODEEMATA.  135 

Periakchus  pileus-sinensis  (Ravenel). 

Plate  LXIII,  figures  la-e,  2a-d. 

jScuteUa pileus-sinensis'Ra.vene'i,  1844,  Acad.  Nat.  Sci.  PliiladelphiaProc,  vol.  2,  p.  97-98,  no  figure. 
Scute.lla  jnleus-sinensis  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 
Sismondia  pileus-sinensis  Com-ad,  1865,  Acad.  Nat.  Sci.  Pliiladelphia  Proc,  p.  74. 
Mortonia  {Periarchus)  pileus-sinensis  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  21. 
Periarchus  pileus-sinensis  Gregory,  1891,  Geol.  Soc.  America  Bull.,  vol.  3,  p.  105. 
IScutella  caput-linensis  Kennedy,  1891,  Texas  Geol.  Survey  Third  Ann.  Rept.,  pp.  55,  56. 
IScutella  caput-sinensis  Kennedy,  1895,  Acad.  Nat.  Sci.  Pliiladelpliia  Proc,  pp.  113,  114,  115. 
Periarchus  pilexis-sinensis  Stetanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  688. 

Determinative  characters. — Test  of  medium  size,  subcircular  in  marginal  outline,  much 
depressed,  less  so  centrally  where  it  rises  in  a  high  well-defined  cone  with  straight  or  concave 
sides;  margin  and  submarginal  area  tliin;  under  surface  flat.  Ambulacral  petals  elongate- 
elhptical,  extending  more  than  haKway  to  the  mai'gin.  Apical  system,  central  or  shghtly  excen- 
tric  anteriorly,  forming  the  summit  of  the  central  conical  area.  Peristome  small,  circular,  ambu- 
lacral furrows  simple  and  straight  for  more  than  one-third  of  the  distance  to  the  margin  then 
forking  symmetrically.  Periproct  very  small,  subcircular,  slightly  more  than  one-third  the  way 
from  peristome  to  posterior  border. 

Dimensions. — Specimen  A:  Length  79  milhmeters;  width  76  millimeters;  height  16  milU- 
meters.     Specimen  B:  Length  65A  milhmeters;  width  67  milhmeters;  height  14  millimeters. 

Description. — Tliis  species  was  fu-st  described  by  Ravenel  from  the  Eocene  deposits  of  South 
Carohna  in  1844.  His  name,  fileus-sinensis  or  "Mandarins  hat,"  is  most  appropriate  for  the 
form,  as  may  readily  be  seen  by  a  glance  at  the  side  view.  The  form  is  rather  abundant  in  certain 
locaUties,  sometimes  occurring  in  association  with  Periarchus  lyelli  and  Periarchus  -protuherans. 
Tlie  test  is  of  medium  size,  ranging  from  2J  to  SJ  inches  in  chameter.  In  marginal  outhne  it  is 
almost  circular,  though  slightly  broader  posteriorly  than  anteriorly.  All  around  the  area  outside 
the  ambulacral  petals  it  is  greatly  depressed  and  nearly  flat;  but  within  the  petaloidal  area  it  rises 
in  a  laigh  well-defined  cone  with  straight  or  concave  sides.  The  height  of  the  cone  is  somewhat 
variable  but  in  the  larger  forms  it  usually  rises  to  over  half  an  inch.  The  margin  of  the  test  is 
tliin  and  slightly  undulating,  both  characters  being  most  pronounced  posteriorly.  In  some 
specimens  the  submarginal  area  is  thinner  than  the  edge.  Tliere  is  usually  a  more  pronounced 
notch  in  the  margin  opposite  the  ends  of  the  posterior  paired  ambulacral  petals.  The  under  sur- 
face is  flat,  even  faintly  concave  between  the  margin  and  the  region  around  the  peristome.  The 
apex  is  slightly  excentric  anteriorly,  at  the  summit  of  the  central  conical  area. 

Tlie  ambulacral  areas  are  narrow  in  the  petaloid  region,  wider  in  the  marginal  region  where 
they  equal  or  slightly  exceed  the  width  of  the  interambulacral  areas.  Tlie  doreal  portions  are 
petaloid.  The  petals  are  subecjual  in  length,  the  anterior  paired  petals  being  shghtlj-  shorter 
than  the  other  three;  elongate  elhptical  in  form;  extending  more  than  haKway  to  the  margin, 
the  odd  petal  usually  approaching  the  margin  more  nearly  than  the  rest;  shghtly  open  at  the 
ends.  The  poriferous  zones  are  rather  wide,  about  equal  to  the  interporiferous  areas;  the  inner 
row  of  pores  oval,  the  outer  slitlike;  the  pairs  of  pores  conjugated.  A  few  pairs  of  pores  occiu- 
beyond  the  ends  of  the  petals. 

The  interambulacral  areas  are  large,  nearly  unifomi,  and  composed  of  large  polygonal  plates. 
The  whole  surface  of  the  test  is  covered  with  small  uniform  tubercles,  which  are  shghtly  larger 
on  the  under  surface. 

The  apical  system  is  subcentral  or  slightly  excentric  anteriorly  at  the  summit  of  the  conical 
area.  The  madreporite  is  relatively  large,  occupA'ing  the  larger  part  of  the  area  covered  by  the 
system  and  is  somewhat  tumid.  There  are  five  genital  pores  near  the  edge  of  the  madreporite 
and  five  small  radial  plates  each  perforated  by  a  small  elhptical  pore. 

Tlie  peristome  is  small,  circular,  central  or  slightly  excentric  anteriorly;  ambulacral  furrows 
simple  and  straight  for  more  than  one-third  the  distance  from  peristome  to  margin,  then  forking 
symmetrically,  each  pair  of  branches  continuing  nearty  to  the  margin,  each  branch  gi^^ng  oti' 
one  important  side  branch  at  right  angles  at  a  point  from  one-tliird  to  one-fourth  the  radius  of 


136  MESOZOIC   AXD   CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

the  test  from  the  margin,  wlaich  side  branches  soon  bend  and  in  turn  approach  the  margin.  A 
small  ridge  extends  along  the  center  of  each  ambulacral  furrow  for  a  short  distance  away  from 
the  peristome. 

Tlie  periproct  is  very  small,  subcircular,  on  the  under  surface  at  a  little  more  than  one-third 
the  distance  from  the  peristome  to  the  posterior  margin.  It  is  sometimes  nearer,  sometimes 
farther  from  the  peristome  than  are  the  forks  m  the  ambulacral  furrows. 

Belated  forms. — P.  inleus-sinensis  is  very  closely  related  to  P.  J]ieUi  and  P.  protuherans. 
From  the  former  it  is  best  distinguished  by  its  higher  and  straight  or  concave-sided  central  cone; 
and  from  the  latter  by  its  lacking  the  swollen  anterior  interporiferous  area  at  the  apex.  No 
foreign  forms  appear  to  be  closely  related  to  this  species. 

Localities. — The  type  was  from  '  'about  6  miles  south  of  Black  Oak  Lock  of  the  San  tee  Canal, 
St.  Johns  Parish,  S.  C."  Tlie  figured  specimen  came  from  "the  Santee  Canal,  S.  C."  Other 
locahties  are  Santee  River,  S.  C;  near  TivoU,  Beachhaven  Park,  Limestone  Creek,  Towers,  Rich 
Hill,  Crawford  County;  Shellstone  Creek,  2  miles  south  of  Perry,  Houston  County;  and  Ring  Jaw 
Landing,  Oconee  River,  Ga. ;  1  mile  west  of  Cocoa,  Choctaw  Coxmty;  and  Claiborne  and  below 
mouth  of  Cedar  Creek,  Clarke  County,  Ala. ;  Cliickasawhay  River  at  Shubuta,  Shubuta  Creek,  2^ 
miles  north  of  Shubuta,  and  Shell  Prairie  near  Pachuta,  ^liss. 

Geologic  horizon. — Jackson  formation,  upper  Eocene.  In  South  Carolina  in  the  Cooper 
marl,  of  Jackson  age.     In  Georgia  in  the  Vicksburg  or  Jackson  formation. 

Collections. — U.  S.  National  Museum  (5133,  A;  137791,  B);  Amherst  College;  Boston 
Society  of  Natural  History;  American  Museum  of  Natural  History;  University  of  South  Carolina. 

Family  CLTPEASTRID^. 

Genus  CLYPEASTEB  Lamarck. 

Clypeastek  eogersi  (Morton). 

Plate  LXIV,  figures  2a-d,  3a-d. 

Scutella  rogersi  Morton,  1834,  Synopsis  organic  remains  Cretaceous,  p.  77,  PI.  XIII,  fig.  3. 

Lagana  rogersi  Agassiz,  1840,  Cat.  syst.  ectyporum  Echinodermatum  fossilium   musei   Neocomensis,  p.  6.     Merely 

listed  Morton's  form, 
non  Scutella  rogersi  Agassiz,  1841,  Men.  echinodermes  vivans  et  fossiles,  vol.  2,  Des  scutelles,  pp.  85,  86,  PI.  XIX, 

figs.  1^.     Described  and  figured  Morlonella  quinquefaria  (Say)  under  the  impression  that  he  was  dealing  with 

Morton's  form. 
Scutella  rogersi  Morton,  1842,  Acad.  Nat.  Sci.  Philadelpliia  Jour.,  1st  ser.,  vol.  8,  p.  218. 
Scutella  jonesii  Forbes,  1845,  Geol.  Soc.  London  Proc,  vol.  4,  p.  574,  text  figure. 
Scutella  jonesii  Forbes,  1845,  Geol.  Soc.  London  Quart.  Jour.,  vol.  1,  p.  440,  text  figure. 
Scutella  rogersi,  Agassiz  (pars),  1847,  Cat.  raisonne  echinodermes,  vol.  7,  p.  135. 
Scutella  rogersi  Bronn  (pars),  1848,  Index  palseontologicus,  vol.  1,  p.  196;  vol.  2,  p.  1126. 
Scutella  jonesii  Bronn,  1848,  Index  palaeontologicus,  vol.  1,  p.  196;  vol.  2,  p.  1126. 
Clypeaster  jonesii  Desor,  1858,  Synopsis  des  ^chinides  fossiles,  p.  243. 

Mortonia  rogersi  Desor  (pars)  (figiu-e  cited  only),  1858,  Synopsis  des  echinides  fossiles,  p.  231. 
Scutella  rodgersi  Gabb,  1859,  Cat.  invert,  fossils  Cretaceous,  p.  19. 
non  Clypeaster  amhigenus  Michelin,  1861,  Soc.  g^ol.  France  Mem.,  2d  ser.,  vol.  7,  p.  113. 
Clypeaster  jonesii  Diijardin  and  Hup6,  1862,  Hist.  nat.  zoophytes  Echinodermes,  p.  573. 
Mortonia  rogersi  Conrad  (pars),  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  74. 
Mortonia  jonesii  Conrad,  1865,  Acad.  Nat.  Sci.  Pliiladelphia  Proc,  p.  74. 
Mortonia  turgida  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  17,  p.  184,  no  figure. 
Clypeaster  jonesii  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  74. 
7  Mortonia  tumida  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  pp.  22,  37  (note). 
Clypeaster  jonesii  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  22. 
?  Clypeaster  tumidus  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  pp.  22,  37  (note). 
Clypeaster  rogersi  Conrad,  1866,  Smithsonian  ;\[isc.  Coll.,  vol.  7  (200),  p.  22. 

Scutella  (mortonia)  rogersi  De  Gregorio  (pars),  1890,  Mon.  faune  Eocenique  Alabama,  p.  250,  PI.  XLIII,  figs.  16-20. 
Clypeaster  rogersi  De  Loriol,  1890,  Soc.  phys.  hist.  nat.  de  Geneva  MEm.,  vol.  suppl.  du  centenaire,  p.  99. 
Scutella  rogersi  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 
Echinanthus  rogersi  Ciregory,  1891  (discussion),  Geol.  Soc  America  Bull.,  vol.  3,  p.  105. 

Mortonia  rogersi  Gregory,  1891  (tabulation),  Geol.  Soc.  America  Bull.,  vol.  3,  p.  105.  This  was  evidently  a  lapsus  calami. 
Scutella  rogersi  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  263. 


EOCENE   ECHINODEEMATA.  137 

Mortonia  rogersi  Dana,  1895,  Manual  of  geology,  4th  ed.,  p.  898,  fig.  1491. 

Chjpeasier  douvilki  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  682,  PI.  XXII,  figs,  la-c;  p.  698. 

Clypeaster  jonesi  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  705. 

Clypeaster  turgidus  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  698. 

Determinative  characters. — Test  medium  in  size;  subpentagonal  to  suboval,  anterior  end 
rounded,  posterior  end  truncated  at  the  corneis  and  centrally,  longer  than  broad,  usually 
•widest  opposite  ends  of  anterior  petals;  much  depressed,  upper  surface  rising  more  or  less  gradu- 
ally from  the  rather  thick  margin  to  the  low  central  apex,  sometimes  regularly  arched  or  of 
.convex  outline  from  margin  to  margin,  sometimes  subcorneal  centrally;  under  surface  flat  around 
the  margin,  concave  centrally.  Ambulacral  petals  large,  tumid,  elliptical,  anterior  pair  shorter 
than  the  rest  wliich  are  about  equal,  all  extending  from  about  one-half  to  two-thirds  the  way  to 
ihe.  margin,  wide  open  at  the  ends ;  poriferous  zones  wide,  outer  rows  of  j^ores  depressed  below 
the  general  surface.  Apical  system  central;  genital  pores  five.  Peristome  medium  in  size, 
central;  ambulacral  furrows  simple,  straight,  well  defined,  reaching  the  margin.  Periproct 
small,  inframarginal ;  situated  from  one-fifth  to  one-sixth  the  distance  from  the  margin  to  the 
peristome. 

Dimensions. — Specimen  A:  Length  70  millimeters;  width  63.5  millimeters;  height  16.5 
millimeters.     Specimen  B:  Length  45  millimeters;  width  43.5  millimeters;  height  17  millimeters. 

Description. — The  species,  to  judge  from  the  number  of  specimens  reported,  is  the  most 
abundant  of  American  clypeasters,  being  rather  common  in  the  Jackson  and  Vicksburg  forma- 
tions of  Mississippi,  Alabama,  and  Georgia.  It  is  also  one  of  the  first  species  of  ecliinoids  dis- 
covered in  American  Cenozoic  deposits,  having  been  figured  and  described  by  Morton  in  1834. 
This  species  has  been  frequently  confused  with  Mortonella  quinquefaria  (Say),  partly  because  of  a 
resemblance  in  general  appearance,  but  more  because  of  certain  mistakes  in  identification  made 
byL.  Agassiz  and  byDesor.  In  1841  Agassiz  described  and  figured  a  specimen  of  Mortonella  qain- 
quefaria  (Say)  under  the  impression  that  he  was  dealing  with  one  of  Clypeaster  rogersi  (Morton). 
In  1858  Desor  made  matters  worse  by  describing  Say's  form  and  founding  upon  it  the  new  genus 
Mortonia;  but,  instead  of  figuring  it,  citing  as  a  good  illustration  Morton's  figure  of  0.  rogersi. 
As  a  result  of  these  mistakes  many  specimens  were  found  mislabelled  in  the  various  collections 
studied  and  the  synonymy  of  the  two  forms  was  found  to  be  in  a  tangle  requiring  considerable 
labor  to  unravel.  M.  quinquefaria  can  easily  be  separated  from  the  present  species  by  its  more 
circular  outline  and  chscoidal  form,  less  tumid  petals,  less  concave  under  surface,  branching 
ambulacral  furrows,  and  the  more  distant  position  of  its  periproct  from  the  posterior  border. 
About  ten  years  after  Morton's  description  of  the  present  species  was  published,  Lyell  collected 
in  Georgia  some  specimens  which  were  described  and  figured  by  Forbes  and  given  the  new  spe- 
cific name  of  Scutella  jonesii,  but  a  careful  study  of  the  figm-es  and  descriptions,  aided  by  an 
extensive  series  of  specimens,  although  -without  the  types,  fails  to  reveal  any  essential  differences 
between  the  two  forms.  Conrad's  Mortonia.  turgida,  which  he  appears  to  have  also  caUed 
Mortonia  tumida  and  still  later  Clypeaster  tumidus  was  probably  a  specimen  of  C.  rogersi,  wliich 
was  tumid  centrally. 

The  test  of  Clypeaster  rogersi  is  of  medium  size,  ranging  from  about  1  i  to  about  3  inches  in 
length.  In  marginal  outline  it  is  somewhat  variable,  being  subpentagonal  in  most  specimens 
though  nearly  oval  in  others ;  the  anterior  end  is  usually  rounded;  the  posterior  end  is  truncated 
centrally,  with  corners  either  truncated  or  rounded;  the  sides  are  either  straight,  slightly  convex, 
or  slightly  concave;  the  longitucUnal  diameter  exceeds  the  transverse;  most  specimens  are 
broadest  opposite  ends  of  anterior  petals,  but  some  are  broadest  centrally.  The  whole  form  is 
greatly  depressed,  the  upper  surface  either  rising  gradually  and  gently  from  the  margin  to  the 
apex  and  showing  an  almost  regularly  arched  or  convex  outline  from  margin  to  margin  when 
viewed  from  the  side  or  end,  or  rising  centrally  in  a  subcorneal  mound  involving  the  petaloidal 
area;  apex  central,  low,  its  height  rarely  exceecUng  one-fourth  the  width  of  the  test;  margin 
thick  and  rounded  anteriorly,  becoming  tliiimer  and  more  wedge-shaped  posteriorh^  The 
under  surface  flat,  or  nearly  so,  around  a  wide  marginal  area,  concave  centrally;  the  concavity 
increasing  more  rapidly  as  the  peiistome  is  approached,  the  depth  of  the  concavity  being  about 
one-tliird  the  height  of  the  test. 


138  MESOZOIC    AXD   CENOZOIC    ECHIXODERMATA    OF    THE    UNITED    STATES. 

The  ambulacral  areas  are  rather  wide,  both  at  the  margin  and  across  the  middle  of  the 
petals,  in  both  cases  wider  than  the  interambulacral  areas;  dorsal  portions  petaloid.  The 
petals  axe  rather  large,  elliptical  to  subspatulate  in  form,  anterior  pair  sUghtly  shorter  than  the 
rest  which  are  about  ecjual  in  length,  all  extending  from  about  one-half  to  two-thirds  the  way 
to  the  margin,  moderately  to  widely  open  at  the  ends.  The  jjoriferous  zones  are  wide,  imier 
rows  of  pores  elevated,  nearly  straight,  either  nearly  parallel  or  slightly  diverging  and  consist 
of  round  openings;  outer  row  of  pores  depressed  below  the  general  surface,  curving  and  com- 
posed of  slitlike  openings;  pairs  of  pores  conjugated;  interporiferous  areas  varjang  in  width 
from  only  slightly  wider  than  poriferous  zones  to  nearly  twice  as  wide,  elevated  so  that  the 
petals  are  somewhat  tumid. 

The  interambulacral  areas  are  wide  opposite  the  ends  of  the  petals,  rather  narrow  at  the 
margin.  The  whole  surface  of  the  test,  including  even  the  ridges  between  the  j^airs  of  pores  of 
the  poriferous  zones,  is  covered  with  very  small,  uniform  imperforate  tubercles,  set  in  rather 
deep  scorbicules.     The  tubercles  are  slightly  larger  on  the  under  surface. 

The  apical  system  is  central,  coincident  ^-ith  the  apex.  There  are  five  genital  pores  at  the 
tips  of  the  points  of  the  almost  star-shaped  madreporite;  and  five  small  ocular  plates  extencUng 
between  the  points  of  the  star,  each  perforated  by  a  minute  pore.  The  apical  system,  together 
^^'ith  a  very  small  area  immediately  surrounding  it  and  involving  the  inner  ends  of  the  petals,  is 
elevated  slightly  above  the  rest  of  the  test. 

The  peristome  is  medium  in  size,  central,  subcircular  to  subpentagonal,  and  situated  at  the 
deepest  portion  of  the  concavity  on  the  under  sm-face.  The  ambulacral  furrows  are  simple, 
straight,  well  defined,  extending  from  peristome  to  margin;  on  well-preserved  specimens  they  can 
be  seen  to  continue  as  a  faint  line  over  the  margin  and  along  the  middle  of  the  ambulacral  petals 
nearly  to  the  apical  system. 

The  periproct  is  small,  subcircular,  inframarginal,  from  one-foiu-th  to  one-sixth  of  the  dis- 
tance from  the  margin  to  the  peristome. 

Related  forms. — Clypeaster  rogersi  is  not  closely  related  to  any  American  species,  but 
resembles  a  number  of  foreign  forms  in  general  appearance,  and  is  very  similar  to  several  of  them. 
C.  hiarritzensis  Cotteau,  from  the  ujDper  Eocene  of  France,  greatly  resembles  the  present  species, 
but  its  ambulacral  petals  are  more  nearly  equal  (or,  if  there  is  any  difference,  the  odd  petal  is  the 
loiigest),  its  interporiferous  areas  are  relatively  wider,  and  its  poriferoiis  zones  relatively  nar- 
rower, more  divergent,  and  therefore  more  widely  apart  at  the  ends.  C.  simplex  Duncan  and 
Sladen,  from  the  OUgocene  of  Western  Sind,  India,  also  closely  resembles  C.  rogersi,  but  differs 
in  ha\ang  petals  which  are  longer  and  tend  to  close  more  nearly  at  the  ends.  Two  species  from 
the  Miocene  of  Cuba,  C.  concaims  Cotteau  and  C.  cotteaui  Egozcue,  resemble  C.  rogersi  in  certain  . 
points;  but  both  are  relatively  higher  than  the  present  species  and  C.  cotteaui  has  straighter  and 
more  ^\■idely  divergent  poriferous  zones.  Michelin  '  stated  that  he  regarded  C.  jonesvi  Forbes 
(which  is  here  regarded  as  a  synonym  of  C.  rogersi)  as  the  young  of  C.  ambigenus  De  Blainville,  a 
recent  West  Indian  species.  The  wi-iter  can  not  agi-ee  with  this  view,  as  C.  ambigenus  is  con- 
siderably higher,  less  concave  on  the  under  suiface,  and  has  more  elliptical  interporiferous  areas 
due  to  the  more  cm-ving  character  of  the  inner  rows  of  pores  of  the  poriferous  zones.  Stefanini's 
C.  douvillei  appears  to  be  a  C.  rogersi  with  relatively  thin  margin  and  subcorneal  upper  surface, 
such  as  the  Avriter  has  found  to  grade  into  the  more  typical  representatives  of  the  species. 

Localities. — Near  Shubuta,  5  miles  west  of  Shubuta,  Vicksbm-g,  and  Jackson,  Miss.;  St. 
Stephens  Bluff,  9  miles  north  of  St.  Stephens,  5  miles  south  of  Claiborne,  Gainestown,  near 
Rescueville,  Choctaw  Comity,  near  Claiborne,  and  Clarksville,  Ala.;  Hawkinsville,  and  5  miles 
southwest  of  Hawkinsville,  Ga. 

Geologic  horizon. — Jackson  formation,  upper  Eocene;  Vicksbm-g  formation,  lower  OUgocene. 
Collections. — ^U.  S.  National  Museum  (137801,  A  and   155377,  B);  Geological  Smvey  of 
Alabama;  Boston  Society  of  Nat\u-al  History;  Academy  of  Natm-al  Sciences  of  Philadelphia; 
Wagner  Free  Institute  of  Science. 

■  ilonographie  des  Clyp&stres  fossiles:  Soc.  g^ol.  France  Mem.,  2d  ser.,  vol.  7,  p.  113, 1861. 


EOCENE   ECHINODEBMATA.  139 

Genus  ECHINANTHTJS  Leske. 

EcHiNANTHus  GEORGiENSis  Twitchell,  n.  sp. 

Plate  LXV,  figure  la-d. 

Determinative  characters. — Test  subpentagoiial,  broadest  posteriorly,  anterior  end  straight, 
posterior  end  jjointed,  notched  and  rostrate,  upper  siirface  depressed,  convex,  with  a  longi- 
tudinal keel  along  the  posteromedian  area;  under  surface  concave  around  the  peristome;  apex 
forward  of  the  center.  Ambulacral  areas  narrow;  dorsal  portions  petaloid,  petals  narrow  and 
rather  short.  Apical  system  small,  anteriorly  excentric.  Peristome  subpentagonal,  transversely 
elongate,  anteriorly  excentric,  with  well-developed  floscelle.  Periproct  small,  oval,  marginal,  at 
the  top  of  a  vertical  sulcus  which  notches  the  posterior  end,  and  beneath  a  slightly  overhanging 
projection  of  the  keel. 

Dimensions. — Length  42  millimeters ;  width  41  milhmeters;  height  IS  millimeters. 

Description. — The  species,  the  first  of  the  genus  Echinanthus  to  be  reported  from  the  United 
States,  is  very  rare,  only  a  single  specimen  having  been  found  up  to  the  present  time.  It  is  of 
especial  interest  because  it  is  one  of  the  eai-liest  of  the  Cenozoic  echinoids,  the  type  having  been 
found  in  the  IMidway  formation  of  Georgia.  The  test  is  subpentagonal  in  marginal  outline, 
broadest  back  of  the  center,  from  which  it  narrows  both  anteriorly  to  the  stiaight  anterior  edge 
and  posteriorly  to  the  pointed  posterior  end;  margin  angular  all  around,  rostrate  posteriorly, 
with  a  notch  at  the  posterior  end  which  can  be  seen  from  both  above  and  below.  The  upper 
siuface  is  depressed,  convex,  declining  rather  steeply  on  all  sides  from  the  apex,  with  a  rounded 
longitudinal  keel  along  the  posteromedian  area,  on  both  sides  of  which  the  surface  is  obUquely 
flattened;  under  surface  concave  around  the  peristome.  The  apex  is  slightly  forward  of  the 
center.  ' 

The  ambulacral  areas  are  narrow  tlu-oughout  then*  whole  length;  dorsal  portions  petaloid; 
petals  narrow,  rather  short,  partly  closing,  the  posterior  pah"  slightly  longer  than  the  anterior 
pair  wliich  are  longer  than  the  odd  petal.  The  poriferous  zones  are  narrow,  outer  pores  oval, 
inner  ones  round,  pairs  of  pores  conjugate. 

Tlie  apical  system  is  small,  excentric  anteriorly,  slightly  more  so  than  the  apex.  There  are 
four  genital  pores,  of  which  the  anterior  pair  are  nearer  together  than  the  posterior;  and  there 
appear  to  be  five  very  small  perforated  radial  plates.  The  madreporite  is  very  small  and  flush 
with  the  sm-face. 

The  surface  of  the  test  is  closely  set  with  very  small,  apparently  imperforate  tubercles  with 
deep  scrobicules.  The  tubercles  are  slightly  larger  on  the  under  sm-face  except  along  a  rather 
narrow  neai'ly  bare  median  band  back  of  the  peristome. 

The  peristome  is  excentric  anteriorly,  beneath  the  apical  system,  subpentagonal,  trans- 
versely elongate,  -with,  a  weU-developed  flosceUe. 

The  peripioct  is  small,  oval,  the  greater  diameter  being  vertical;  marginal,  or  shghtly  supra- 
marginal,  beneath  a  slightly  overhanging  projection  of  the  keel,  at  the  top  of  a  vertical  sulcus 
which  notches  the  posterior  end  of  the  test. 

Related  forms. — Echinanthus  georgiensis  is  quite  distinct  from  all  other  American  echinoids, 
the  notched  posterior  end  and  the  details  of  the  periproct  affording  a  ready  means  of  separation 
from  all  forms  which  in  any  way  resemble  it.  Among  foreign  forms  it  resembles  Echinanthus 
suhcarinatus  Goldfuss  from  the  Oligocene  of  Germany  but  has  a  less  regularly  oval  outline  and  a 
less  pronounced  posterior  rostration. 

Locality. — Five  miles  south  of  Ellaville,  Ga. 

Geologic  horizon. — Midway  formation,  lower  Eocene. 

Collection.— ^J .  S.  National  Museum  (1656836b). 


140  MESOZOIC   AND   CENOZOIC    ECHINODEEBIATA    OF    THE   UNITED    STATES. 

Order  ATELOSTOMATA. 

Suborder  ASTERNATA. 

Family  CASSIDITLID^. 

Genus  CASSIDXJLUS  Lamarck.  , 

Cassidulus  californicus  F.  M.  Anderson. 

Plate  LXV,  figure  2a-b. 

Casddulus  californicus  F.  M.  Anderson,  1905,  California  Acad.  Sci.  Proc,  3d  ser.,  Geology,  vol.  2,  No.  2,  p.  194,  PI. 

XIII,  figs.  6,  7. 
Cassidulus  californicus  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  396,  p.  13,  112,  PL  IV,  figs.  1,  la. 

Cassidulus  californicus  Arnold  and  R.  Anderson,  1910,  U.  S.  Geol.  Survey  Bull.  398,  pp.  70,  284,  PL  XXVI,  figs.  1,  la. 
Cassidulus  californicus  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  696. 

Description. — ^As  the  writer  has  not  been  able  to  obtain  possession  of  any  specimens  of  this 
species  the  description  of  Anderson  is  given  verbatim: 

Test  small,  elliptical,  robust  and  often  somewhat  globular;  lower  surface  flattened,  or  concave,  upper  siu-face  convex; 
mouth  not  central,  round,  and  occupying  a  position  three-fifths  of  the  distance  from  the  anal  margin ;  anal  pore  terminal; 
apical  star  nearly  symmetrical,  central,  on  dorsal  surface;  tuberculation  distinct,  the  tubercles  lying  within  rounded 
pits.    There  is  a  tendency  to  form  shoulder-like  expansions  on  the  periphery  behind  the  position  of  the  mouth. 

Anderson  does  not  mention  a  floscelle  nor  do  his  figures  show  one,  but  tlie  figured  specimen 
of  Arnold  shows  a  flosceUe  distinctly.  Arnold's  figures  also  show  a  test  with  a  suboblong  margi- 
nal outline  and  a  supramarginal  periproct,  apparently  transverse,  beneath  an  overhanging 
expansion  of  the  test.     Arnold's  form,  here  refigured,  was  21  millimeters  long. 

Locality. — Four  mUes  west-northwest  of  CoaHnga,  Cal. 

Geologic  horizon. — Tejon  formation,  upper  Eocene. 

Collections. — Cahfornia  Academy  of  Natural  Sciences;  U.  S.  National  Museum  (165664). 

Cassidulus  (Rhtnchopygus  ?)  holmesi  TwitcheU,  n.  sp. 
Plate  LXV,  figures  3a-d. 

Determinative  cTiaracters. — Test  small,  broadly  oval,  slightlj'  truncated  at  the  posterior  end; 
upper  surface  convex,  sides  and  ends  rounded  and  inflated;  under  surface  concave  around  the 
peristome.  Ambulacral  areas  narrow,  petaloid;  petals  nearly  equal,  partly  open.  Apex  cen- 
tral; apical  system  excentric  anteriorly.  Peristome  excentric  anteriorly,  pentagonal,  longitu- 
dinally elongate,  with  a  flosceUe.  Periproct  elliptical,  transverse,  supramarginal;  located  in  a 
rather  deep,  oval  indentation  whose  edges  are  almost  flush  with  the  posterior  surface  of  the  test. 

Dimensions. — Length  25  mdhmeters:  wddth  22.5  millimeters;  height  14  millimeters. 

Description. — Only  a  single  specimen  of  this  interesting  species  is  kno\vn  to  the  writer.  It 
was  found  in  the  F.  S.  Holmes  collection,  now  owned  by  the  American  Museum  of  Natural 
History,  and  as  it  was  probably  collected  by  Holmes  is  named  in  liis  honor.  The  test  is  small, 
broadly  oval,  being  but  shghtly  longer  than  it  is  broad,  slightly  truncated  at  the  posterior  end. 
The  upper  surface  is  regularly  convex,  somewhat  elevated,  sides  and  ends  sloping  nearly  uni- 
formly to  the  rounded  and  inflated  margin;  under  surface  tumid  around  the  margin,  concave 
around  the  peristome;  apex  central. 

The  ambulacral  areas  are  rather  narrow,  dorsal  portions  petaloid;  petals  nearly  equal  in 
length,  the  posterior  pair  bemg  but  shghtly  longer  than  the  others,  nearly  closing  at  the  ends. 
The  poriferous  zones  are  rather  broad,  outer  row  of  pores  oval,  inner  row  round,  paii's  of  pores 
conjugate. 

The  surface  of  the  test  is  closely  set  mth  small  tubercles  in  deep  scrobicules,  which  are 
larger  on  the  under  surface  except  along  a  cribriform  median  band. 

The  apical  system  is  excentric  anteriorly.  There  are  four  genital  pores  of  which  the  ante- 
rior pair  are  nearer  together  than  the  posterior.  No  further  details  can  be  made  out  on  the  single 
specimen  known. 


EOCENE   ECHINODEKMATA.  141 

The  peristome  is  excentric  anteriorly,  immediately  beneath  the  apical  system,  pentagonal, 
longitudinally  elongate,  with  a  floscelle. 

The  periproct  is  elliptical,  transverse,  supramarginal,  located  in  a  rather  deep,  oval  indenta- 
tion at  the  top  of  the  slight  posterior  truncation.  The  edges  of  the  indentation  are  almost  even 
with  the  posterior  margin.  Below  the  periproct  a  vaguely  defined,  broad,  shallow  groove  extends 
downward  across  the  margin. 

Related  forms. — Cassidulus  Jiolmesi  is  not  closely  allied  to  any  American  form.  Its  broadly 
oval  and  uniformly  convex  form,  nearly  equal  ambulacral  petals,  and  the  details  of  its  periproct 
and  peristome  readity  distinguish  it.  It  does  not  appear  to  be  closely  related  to  any  foreign 
form. 

Locality. — Santee  River  (?),  S.  C. 

Geologic  horizon. — Probably  in  the  McBean  formation  of  Claiborne  group,  middle  Eocene. 
The  matrix  is  a  fine-grained  greensand  such  as  is  known  to  occur  on  Santee  River. 

Collection. — American  Museum  of  Natural  History. 

Cassidulus  (Rhynchopygus)  lyelli  (Conrad). 

Plate  LXV,  figm-es  4a-d. 

Nucleolites  lyelli  Conrad,  1850,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  2,  p.  40,  fig.  14. 

Cassidulus  lyelli  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  75. 

Pygorhynchus  lyelli  Cotteau,  1888,  Paleontologie  fran^aise,  Echinides  ^ocfenes,  vol.  1,  p.  550. 

Nucleolites  lyelli  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  200. 

Pygorhynchus  lyelli  Stefanini,  1911,  Soc.  geol.  italiana  BoU.,  vol.  30,  p.  696. 

Determinative  characters. — Test  low,  oval  in  marginal  outUne,  truncated  at  the  posterior  end; 
upper  surface  convex,  depressed;  under  surface  slightly  concave  around  the  peristome;  apex 
slightly  excentric  posteriorly.  Ambulacral  areas  narrow,  dorsal  portions  petaloid;  petals  long, 
elliptical.  Poriferous  zones  narrow;  pores  subequal;  interporiferous  areas  rather  wide.  Apical 
system  excentric  anteriorly.  Peristome  excentric  anteriorly,  beneath  the  apical  system,  sub- 
pentagonal  to  subtriangidar,  with  a  floscelle.  Periproct  suboblong  to  dumbbell  shaped,  trans- 
versely elongate,  supramarginal,  nearly  flush  with  the  truncated  posterior  face  of  the  test;  with 
an  overhanging  rostrum. 

Dimensions. — Length  33  milhmeters;  width  28  millimeters;  height  1.5  millimeters. 

Description. — The  present  whereabouts  of  the  type  of  Conrad's  Cassidulus  lyelli  is  unknown; 
but  as  the  present  species  answers  so  well  to  Conrad's  description  and  drawings  and  as  it  came 
from  about  the  same  locality,  it  is  thought  highly  probable  that  it  is  the  same.  However,  as 
only  a  single  somewhat  imperfect  specimen  is  known,  further  collecting  may  show  that  it  is  not 
Conrad's  form,  in  which  case  the  present  species  will  have  to  receive  a  new  name.  The  test  is 
regidarly  oval  or  subeUiptical  in  marginal  outline,  vertically  truncated  at  the  posterior  end.  The 
upper  surface  is  low,  almost  uniformly  convex,  depressed,  shghtly  more  elevated  posteriorly 
than  anteriorly;  under  surface  slightly  convex  posteriorly,  faintly  concave  around  the  peristome. 
The  apex  is  sUghtly  excentric  posteriorly. 

The  ambulacral  areas  are  narrow,  dorsal  portions  petaloid,  petals  long,  symmetrically 
elliptical,  somewhat  open  at  the  ends,  the  posterior  pair  longer  than  the  others,  which  are  nearly 
equal  in  length.  The  poriferous  zones  are  narrow,  similar;  pores  subequal  in  size,  outer  row 
oval,  mner  row  round,  pairs  of  pores  conjugate;  interporiferous  areas  relativel}'  rather  wide. 

The  surface  of  the  test  is  closely  set  with  small  scrobiculate  tubercles,  which  are  larger  on 
the  under  surface.  The  under  surface  is  poorly  preserved  on  the  single  specimen  obtained; 
but  there  appears  to  have  been  a  median  band  back  of  the  peristome  which  was  somewhat 
smoother  than  the  adjacent  areas  and  was  more  or  less  pitted. 

The  apical  system  is  excentric  anteriorly,  being  about  three-eighths  the  length  of  the  test 
fi-om  the  anterior  end.  The  details  can  not  be  made  out,  beyond  the  fact  tiiat  there  are  four 
genital  pores  of  which  the  anterior  pair  are  nearer  together  than  the  posterior. 

The  peristome  is   excentric   anteriorly,   immediately  beneath  the   apical  sj'stem.     It  is 
poorly  preserved;  but  there  is  enough  to  show  that  it  is  subpentagonal,  though  approaching  a 
subtriangular  form,  and  surrounded  by  a  somewhat  inconspicuous  floscelle. 
39800°— 1.5 10 


142  MESOZOIC   AND    CENOZOIC    ECHINODEKMATA    OF    THE    UNITED    STATES. 

The  periproct  is  subelliptical  to  siiboblong,  considerably  elongated  transvereely,  supra- 
marginal,  at  the  top  of  and  nearly  flush  ^vith  the  vertically  truncated  posterior  surface  of  the 
test.  The  rounded  central  part  of  the  upper  edge  extends  downward  so  as  to  break  the  ellipti- 
cal contour  of  the  periproct,  and  projects  shghtty  beyond  the  periproct  so  as  to  shghtly  overhang 
the  vaguely  defined  broad  and  shallow  groove  wliich  extends  below  the  periproct  across  the 
posterior  margin. 

Related  forms. —  Cassidulus  lyeUi  is  quite  disthict  from  all  other  representatives  of  the 
genus  from  American  strata.  Its  transversely  suboblong  periproct  and  its  low  regularly  oval 
form  readily  permit  of  its  identification.  It  does  not  appear  to  be  closely  related  to  any  foreign 
form. 

Locality. — In  Baker  County,  Ga. 

Geologic  lioricon. — Jackson  formation,  upper  Eocene. 

Collection. — Boston  Society  of  Natural  History  (15.52a). 

Cassidulus  (Rhynchoptgus)  raveneli  Twitchell,  n.  sp. 

Plate  LXV,  figures  5a-cl;  Plate  LXA'I,  figures  la-f,  2a-b. 

Pygorhynchus  crucifer  Bavenel,  1S48,  Ecliinidse,  recent  and  fossil,  of  South  Carolina,  p.  4,  PI.  II,  figs.  9,  10. 
Pygorhynchus  crucifer  Eavenel,  1850,  Cat.  recent  and  fossil  Echinidae  of  South  Carolina:  Am.  Assoc.  Adv.  Sci.  Proc, 

vol.  3,  p.  160. 
Ravenelia  crucifer  McCrady,  18.59,  Elhott  Soc.  Nat.  Hist.  Charleston  Proc,  veil.  1,  pp.  2S2,  283,  no  figure. 
Pygorhynchus  crucifer  Agassiz,  1883,  Mus.  Comp.  Zool.  Mem.,  vol.  10,  No.  1,  p.  91. 
non  NucleoUtes  crucifer  Morton,  1834,  Synopsis  organic  remains  Cretaceous,  p.  75,  PI.  Ill,  fig.  15. 
non  Trematopygus  crucifer  Clark,  1891,  Johns  Hopkins  I'niv.  Circ,  vol.  10,  No.  87,  p.  76. 
non  Trematopygus  crucifer  Clark,  1893.  U.  S.  Geol.  Survey  Bull.  97,  p.  63. 

Determinative  characters. — Test  hemieUipsoidal,  elUptical  in  margmal  outline,  truncated 
at  posterior  end;  upper  surface  considerably  depressed,  convex,  dechnmg  more  gently  to  the 
ends  than  to  the  sides;  imder  surface  slightly  concave  longitudinally.  Ambulacra  petaloid, 
the  posterior  petals  longer  than  the  others  and  bending  outward  toward  their  ends.  On  the 
under  side  there  is  a  wide,  longitudinal,  median  band,  where  the  tubercles  are  replaced  by  a 
more  or  less  pitted  surface.  Apex  central;  apical  system  excentric  anteriorly.  Peristome 
pentagonal,  excentric  anteriorly,  with  a  well-defuied  floscelle.  Periproct  supramarginal, 
rather  large,  elliptical,  transverse,  concealed  beneath  an  overhanging  rostrum  at  the  head  of  a 
short,  broad  sulcus. 

Dimensions. — Specunen  A  (type):  Length  40  millimeters;  width  29  milUmeters;  height  14 
milluneters.  Specimen  C:  Length  55  milUmetei-s.  Largest  specimen  seen:  Length  55  milli- 
meters; width  39  milhmetei-s;  height  IS' millimeters. 

Description. — Dr.  Edmund  Ravenel,  of  Grove,  S.  C,  in  1S4S,  in  a  pamphlet  of  which 
but  a  few  copies  were  printed,^  gave  some  good  figures  of  a  form  which  is  evidently  the  same 
as  the  one  here  described.  He  gave  no  description  and  did  not  regard  the  form  as  new;  but 
said  it  was  the  same  as  NucleoUtes  crucifer  Slorton  and  placed  it  in  the  genus  Pygorhjmchus. 
Ravenel  was  undoubted^  mistaken  in  regarding  his  form  as  the  same  as  that  of  Morton,  for 
there  is  hardly  more  than  a  superficial  resemblance  between  them.  W.  B.  Clark  assigns  Morton's 
form  to  the  genus  Trematopygus,  whereas  the  form  which  Ravenel  figured  and  which  is  here 
described  for  the  firet  time  is  a  Cassidulus  of  the  Rhynchopygus  tj^e.  However,  in  view  of 
Ravenel  having  been  the  discoverer  of  the  form  and  in  recognition  of  liis  interest  in  and  additions 
to  the  knowledge  of  the  fossil  Echinoidea  of  South  CaroUna  this  interesting  species  is  named 
after  him. 

The  test  of  this  species  is  hemieUipsoidal  in  form,  regularly'  elliptical  in  marginal  outlme, 
and  truncated  and  slightty  indented  at  the  posterior  end.'  The  upper  surface  is  low,  depressed, 
and  rather  uniformly  convex,  though  more  abruptly  so  transvei-sely  than  longitudinally;  under 
surface  slightly  concave  along  the  longitudinal  median  area,  the  concave  portion  being  limited 
along  the  sides  by  the  somewhat  inferiorly  projecting  side  edges.     The  apex  is  central. 

*  The  Library  of  Congress  at  Washington  possesses  the  copy  which  was  studied  by  the  writer. 


EOCENE   ECHINODEEMATA.  143 

The  ambulacra!  areas  are  petaloid,  the  petals  rather  long  and  narrow,  converging  toward 
their  extremities,  where  they  remain  partly  open;  the  posterior  pair  longer  than  the  rest  and 
bending  outwardly  near  their  extremities ;  the  odd  petal  shorter  than  the  posterior  but  slightly 
longer  than  the  anterior  pair.  The  poriferous  zones  are  rather  narrow,  but  slightly  more  than 
half  the  wiclth  of  the  narrow  interporiferous  areas;  outer  row  of  pores  shtlike,  inner  row  round: 
pairs  of  pores  conjugated  by  narrow  grooves  separated  by  low,  easily  effaced  ridges. 

The  interambulacral  areas  are  broad;  the  posterior  area  slightly  inflated  from  the  apex  to 
the  periproct,  where  it  projects  as  an  overhanging  rostrum.  The  tubercles  on  the  upper  sides 
of  the  test  are  numerous,  luiiformly  small,  close  together,  and  with  deep  scrobicules;  the  inter- 
vening spaces  being  covered  with  still  smaller  granulations.  On  the  under  side  the  tubercles  arc 
larger,  except  along  a  rather  wide,  longitudinal,  median  band,  which  is  free  from  tubercles  but 
dotted  with  numerous  pits. 

The  apical  system  is  excentric  anteriorly,  compact,  and  consists  of  four  basal  plates  per- 
forated by  large  pores,  the  two  anterior  pores  being  slightly  nearer  together  than  the  posterior; 
five  small  radial  plates,  each  perforated  by  a  minute  pore ;  and  a  large  madreporite,  which  occupies 
the  center  of  the  system. 

The  peri-^tome  is  of  medium  size,  pentagonal,  excentric  anteriorly,  directly  beneath  the 
apical  system,  with  a  well-defined  floscelle.  The  floscelle  is  composed  of  five  prominent  rounded 
boun-clets  mth  granulated  surfaces  alternating  with  five  large  well-developed  phyllodes.  In 
addition  to  outer  rows  of  pores  each  phjdlode  has  two  inner  rows  ending  in  two  rather  large  pores, 
which  are  located  just  between  adjacent  bourrelets. 

The  periproct  is  rather  large,  elliptical,  transversely  elongate,  supraniarginal,  and  con- 
cealed beneath  an  overhanging  rostrum  at  the  head  of  a  broad  and  rather  shallow  sulcus,  which 
extends  beyond  the  rostrum  to  the  truncated  posterior  margin  of  the  test. 

Related  forms . — Cassidulus  raveneli  from  its  size,  shape,  and  details  of  structure  is  readily 
separated  from  the  other  representatives  of  the  genus  occurring  in  the  American  and  European 
Cenozoic  deposits.  In  several  features  it  resembles  RhyncJiopygiis  calderi  d'Archiac  and  Haime 
from  the  Tertiary  deposits  of  India,  but  it  is  more  depressed  and  has  a  more  regularly  elliptical 
marginal  outline.  In  a  less  degree  it  resembles  Eurhodia  monisii  d'Archiac  and  Haime,  also  from 
the  Tertiary  deposits  of  India,  but  it  is  more  depressed  and  lacks  the  very  elongated  peristome  so 
characteristic  of  the  Indian  form.  The  nearest  American  form  is  Cassidulus  depressus,  from 
which  it  is  readily  distinguished  by  its  greater  size  and  the  details  of  its  periproct. 

Localities. — South  Carolina  (Ravenel);  San  tee  Canal  (figured  specimens),  S.  C;  Rocky 
Point  and  Wilmington,  N.  C. 

Geologic  horizon. — In  North  Carolina  in  the  Castle  HajTie  limestone,  upper  Eocene  or 
Oligocene.  In  South  Carolina  probably  in  the  Cooper  marl  (upper  Eocene)  or  the  upper  part 
of  the  McBean  formation  (middle  Eocene) . 

Collections. — American  ^Museum  of  Natural  History  (A,  B,  ami  C);  U.  S.  National 
Museum;  Johns  Hopkins  University. 

Cassidulus  (Rhynchopygus  ?)  patei.liformis  (Bouve). 
Plate  LXVI,   figures  3  a-d. 

Catopygus  patelliformis  Bouv6,  1851,  Boston  Soc.  Nat.  Hist.  Proc,  vol.  4,  p.  2,  text  figures. 

Cassidulus  patelliformis  Desor,  18.58,  Synopsis  des  echinides  fossiles,  p.  290. 

Cassidulus  patelliformis  Dujardin  and  Hup4,  1862,  Hist.  nat.  zoophytes  echinodermes,  p.  .583. 

Cassidulus  patelliformis  Conrad,  1SC.5,  Acad.  Nat'.  Sci.  Philadelphia  Proc.,  p.  7-5. 

Cassidulus  patelliformis  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7,  p.  22. 

Cassidulus  patelliformis  Cotteau,  1888,  Paleontolugie  frangaise,  Echinides  eocenes,  vol.  1,  p.  .521. 

Cassidulus  patelliformis  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  ji.  700. 

Determinative  characters. — Test  elliptical,  narrowing  and  rather  pointed  posteriorly;  upper 
surface  somewhat  elevated,  convex,  elongate-subconical;  under  surface  flat,  meeting  the  upper 
surface  in  an  angular  margin;  apex  slightly  forward  of  the  center.  Ambulacral  areas  narrow, 
petaloid;  petals  rather  long,  the  anterior  pair  shorter  than   the  posterior  pair  and  odd  petal 


144  MESOZOIC   AXD   CENOZOIC    ECHINODEKMATA    OF    THE    UNITED    STATES. 

which  are  nearly  equal  in  length,  closing  at  the  ends.  Peristome  apparently  sUghtly  excentric 
anteriorly.  Periproct  small,  elliptical,  transverse,  supramarginal,  in  a  shallow  indentation 
close  to  the  posterior  end  of  the  test. 

Dimensions. — ^Length  32  miUimeters;  width  21  millimeters;  height  15  millimeters. 

Description.— This  species  was  first  reported  in  1851  by  T.  T.  Boiive  of  Boston. .  The  doubt 
in  regard  to  the  generic  position  of  Bouv6's  form,  which  Desor  recognized  as  existing  because 
of  a  lack  of  definite  knowledge  in  regard  to  the  inferior  surface,  is  partly  resolved  by  an  exami- 
nation of  the  type,  which  though  not  showmg  a  floscelle  does  show  a  cribriform  median  area 
on  the  under  surface.  A  valuable  corroboration  of  this  evidence  is  found  in  the  fact  that  one 
specimen  of  Cassidulus  depressus,  the  form  most  nearly  related  to  the  present  species,  showa 
a  well-defined  floscelle.  The  test  of  this  species  is  elliptical  in  marginal  outline,  narrowing 
noticeably  toward  the  posterior  end.  The  upper  surface  is  somewhat  elevated,  convex,  elongate- 
subconical,  sloping  steeply  to  the  margin,  slightly  less  so  posteriorly  than  on  the  sides  and 
anteriorly;  under  surface  flat,  meetmg  the  sides  at  the  margin  in  an  acute  angle;  apex  slightly 
forward  of  the  center.  The  general  appearance  of  the  form,  as  the  name  given  by  Bouv4 
impHes,  is  much  like  that  of  a  limpet  shell  such  as  those  of  the  genus  Patella. 

The  ambulacral  areas  are  narrow,  narrower  at  the  ambitus  than  in  the  petaloid  region; 
dorsal  portions  petaloid,  the  petals  rather  long,  the  anterior  pair  shorter  than  the  posterior 
pair  and  odd  petal,  which  are  neariy  equal  in  length;  petals  closing  at  their  extremities.  The 
details  of  the  ambulacra  and  apical  system  are  not  discernible  on  the  specimen. 

The  peristome  is  apparently  slightly  eccentric  anteriorly;  details  can  not  be  made  out. 
The  periproct  is  small,  elliptical,  transverse,  supramarginal;  located  in  a  small,  shallow,  trans- 
verse indentation  only  slightly  above  the  margin  and  very  close  to  the  rather  pointed,  truncated, 
posterior  end  of  the  test. 

The  surface  of  the  test  is  covered  with  numerous  small  tubercles,  with  scrobicules,  larger 
on  the  under  surface  except  along  a  rather  broad  median  area  back  of  the  peristome  where  the 
surface  is  free  from  tubercles  and  more  or  less  cribriform. 

Related  forms. — No  other  species  of  Cassidulus  reported  from  the  United  States  bears  any 
close  resemblance  to  Cassidulus  patelliformis.  It  is  closely  related  to  Cassidulus  depressus  but 
can  easily  be  distinguished  by  its  greater  size,  more  elevated  and  elongated  subcorneal  upper 
surface,  more  steeply  sloping  posterior  face,  and  lower  placed  periproct. 

Locality. — Georgia,  probably  Baker  County. 

Geographic  horizon. — Probably  upper  Eocene.     May  be  lower  Oligocene. 

Collection. — Boston  Society  of  Natural  History  (1558). 

Cassidulus  (Rhynchopygus)  depressus  Twitchell,  n.  sp. 
Plate  LXVI,  figures  4a-e,  5a-b. 

Determinative  characters. — Test  very  small,  subelliptical,  upper  surface  much  depressed, 
convex,  declining  gently  on  the  sides,  the  posterior  end  slopmg  more  steeply  than  the  anterior; 
undersm-face  slightly  concave.  Apex  central;  apical  system  excentric  anteriorly.  Peristome 
small,  pentagonal,  slightly  elongate  longitudmally,  anteriorly  excentric,  with  a  well-defined 
floscelle.  Between  the  peristome  and  the  posterior  border  there  extends  a  wide,  elUptical, 
cribriform  area.  Periproct  small,  elliptical,  transverse,  situated  rather  high  above  the  posterior 
margin,  in  a  shallow  indentation. 

Dimensions.— ^]yec\mn\  A   (type):  Length   16  millimetere ;  width   12  millimeters;  height 

7  millimeters. 

Description. — This  small  Cassidulus,  one  of  the  smallest  representatives  of  the  genus 
occurring  in  American  deposits,  has  a  test  which  is  subelliptical  in  marginal  outline.  The 
upper  surface  is  much  depressed,  longitudinally  convex,  declining  gently  on  the  sides.  The 
posterior  median  area,  between  the  apical  system  and  the  periproct  remains  at  nearly  the 
same  elevation  from  which  the  sm-face  slopes  steeply  to  the  posterior  margm  and  less  steeply 
to  the  anterior.  The  undersurface  is  nearly  flat,  or  slightly  concave  longitudinally,  meeting 
the  sides  at  the  margin  in  a  somewhat  acute  angle.     The  apex  is  central  or  subcentral. 


EOCENE   ECHINODEEMATA.  145 

The  ambulacral  areas  are  obscure  on  the  specimens  studied;  but  are  apparently  narrow 
with  petaloid  dorsal  portions.  The  narrow  poriferous  zones  show  an  outer  row  of  slitlike 
pores  and  an  inner  row  of  round  pores.  The  other  details  can  not  be  made  out.  The  apical 
system  is  excentric  anteriorly;  its  details  are  not  discernible. 

The  peristome  is  small,  pentagonal,  slightly  elongate  longitudinally,  anteriorly  excentric, 
beneath  the  apical  system,  with  a  well-defined  floscello  having  promuient  bourrelets  and  rather 
extensive  rounded  phyllodes. 

The  periproct  is  small,  elliptical,  transverse,  situated  rather  high  above  the  posterior 
mai-gin  m  an  indentation  in  the  test. 

The  surface  of  the  test  is  covered  with  numerous  small  tubercles,  with  scrqbicules,  larger 
on  the  under  surface.  Between  the  peristome  and  the  posterior  border  there  extends  a  wide 
elliptical,  cribriform  area. 

Related  forms. — This  form  is  most  closely  related  to  Cassidulus  fatelliformis  (Bouve) 
from  which  it  is  readily  distmguishod  by  its  smaller  size,  more  depressed  form,  the  higher 
position  of  its  periproct,  and  the  greater  relative  elevation  of  the  upper  surface  between  the 
periproct  and  the  apical  system.  It  also  resembles  Cassidulus  raveneli  but  is  very  much  smaller, 
and  its  periproct  has  a  less  conspicuous  overhanging  rostrum  in  a  shallower  depression.  In 
several  respects  it  resembles  Rhynchopygus  fygmxus  Duncan  and  Sladen  from  the  Tertiary  of 
India,  but  it  is  more  depressed  and  much  narrower  posteriorly. 

Locality. — Baker  County,  Ga. 

Geologic  horizon. — Probably  upper  Eocene.     May  be  lower  Oligocene.  ,   : 

Collection. — Boston  Society  of  Natural  History  (1557a,  A;  .1557b,  B). 

Cassidulus  (Pygoehynchxts)  coneadi  Conrad.  .  r 

Plate  LXVII,  figures  la-f. 

Catopygus  conradi  Couper  MSS.,  fid.  Conrad. 

Catopygus  conradi  Conrad,  1850,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  2,  p.  39,  PI.  I,  fig.  9.  \— 

Cassidulus  conradi  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  75. 

Cassidulus  conradi  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  22.     '  / ' 

Catopygus  conradi  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  90. 

Cassidulus  conradi  Stefanini,  1911,  Soc.  geol.  ita,liana  Boll.,  vol.  30,  p.  700. 

Determinative  characters. — Test  ovate  in  marginal  outline,  broad  anteriorly,  narrowino- 
abruptly  posteriorly;  sides  and  anterior  end  somewhat  flattened,  posterior  end  trvmcated; 
upper  surface  convex,  depressed,  flattened  on  top ;  under  surface  flattened,  sKghtly  concave 
around  the  peristome;  apex  xisually  forward  of  the  center.  Ambulacral  areas  narrow.  Apical 
system  very  excentric  anteriorly.  Peristome  excentric  anteriorly,  less  so  than  the  apical  system 
pentagonal,  transversely  elongate,  with  a  floscelle.  Periproct  elliptical,  transverse,  supra- 
marginal;  beneath  an  overhanging  expansion  of  the  test,  whose  edge  is  even  with  the  posterior 
margin. 

Dimensions. — Length  41  millimeters;  width  35  millimeters;  height  2.3  millimeters. 

Description. — This  species  was  first  figured  in  1850  by  Conrad,  who  also  gave  a  good  descrip- 
tion of  the  form.  He,  however,  credits  the  species  to  a  manuscript  description  by  J.  Hamilton 
Couper  and  says  that  the  name  given  was  adopted  at  the  particular  request  of  Mr.  Couper. 
The  test  is  ovate  in  marginal  outline,  broad  anteriorly,  narrowing  abruptly  posteriorly;  maro-in, 
somewhat  flattened  anteriorly,  more  so  on  the  sides  which  are  nearly  vertical  at  the  ambitus 
but  round  over  the  edges  to  the  upper  and  lower  surfaces,  obliquely  trimcated  posteriorly  and 
truncated  vertically  at  the  posterior  end.  The  upper  surface  is  convex,  depressed,  flattened 
on  top,  and  in  the  form  of  a  low,  rounded  ridge  above  the  periproct;  undersurface  flattened, 
slightly  concave  around  the  peristome  and  slightly  convex  posteriorly.  The  lower  edge  at  the 
posterior  end  is  somewhat  prominent,  angular  and  slightly  rostrate.  The  apex  is  usually 
forward  of  the  center,  when  it  is  coincident  with  the  apical  system;  but  even  then  it  is  only 
slightly  higher  than  the  surface  of  the  posterior  mterambulacrum,  and  in  some  forms  the  upper 
surface  is  so  depressed  anteriorly  as  to  make  the  apex  excentric  posteriorly. 


146  MESOZOIC  AXD   CENOZOIC   ECHIXODEEMATA   OF   THE   Uis'ITED   STATES. 

The  ambulacral  areas  are  narrow,  dorsal  portions  petaloid;  petals  long,  narrow,  and  open 
at  their  ends,  the  posterior  pah-  being  longer  than  the  others  whicli  arc  nearly  equal  in  length. 
The  poriferous  zones  are  nari'ow,  the  adjacent  zones  of  the  anterior  and  posterior  paired  petals 
being  slightly  broader  and  straighter  than  the  othere;  pores  small,  outer  row  slitlike,  inner 
row  romid,  pairs  of  pores  conjugate. 

The  ai^ical  system  is  very  excentric  anteriorly,  being  located  less  than  a  tliird  of  the  length 
of  the  test  from  the  anterior  end.  There  are  fom-  genital  pores,  of  which  the  anterior  pair 
are  nearer  together  than  the  jjosterior;  and  there  are  five  small  perforated  radial  plates.  These 
are  the  only  details  that  can  be  made  out  on  the  specimens. 

The  sm-face  of  the  test  is  closely  set  with  very  small  imperforate  tubercles  with  deep 
scrobicules.  The  tubercles  are  slightly  larger  on  the  under  sm-face  except  along  a  narrow 
median  band  back  of  the  peristome,  which  is  free  from  tubercles,  nearly  smooth  and  dotted  with 
numerous  very  small  pits. 

The  peristome  is  excentric  anteriorly,  less  so  than  the  apical  system,  pentagonal,  trans- 
vei-sely  elongate,  with  a  well-defined  floscelle. 

The  periproct  is  rather  large,  elliptical,  transverse,  supramarginal,  at  the  top  of  the  pos- 
terior truncation;  beneath  a  romided,  transverse,  somewhat  protruding  expansion  of  the  test 
whose  edge  is  about  even  with  the  truncated  posterior  margin. 

Related  forms. — Cassidulus  conradi  is  readily  distinguished  from  the  other  representatives 
of  the  genus  from  American  strata.  It  is  most  nearly  related  to  Cassidulus  carolinensis,  but 
can  be  separated  by  its  more  excentric  apical  system  and  more  transverse  peristome  and  by 
being  narrower  posteriorly  and  less  concave  around  the  j)eristome.  Its  nearest  European  ally 
appears  to  be  Pygorliynclms  rnaveri  de  Loriol  from  the  Tertiarj'  of  S\\-itzer]and,  but  the  latter 
has  both  its  apical  system  and  peristome  less  excentric  anteriorly  and  does  not  have  its  peristome 
transversely  elongated.  C.  conradi  also  resembles  PygorJiipicJius  grignonensis  (Defrance) 
Agassiz  from  the  Eocene  of  France,  but  is  narrower  jjosteriorly  and  has  its  apical  system  less 
excentric  anteriorly. 

Localities. — Palmjn-a,  Lee  County,  Ga.  (Conrad);  Baker  County,  Ga. 

Geologic  liorizon.- — Upper  Eocene  or  lower  Oligocene  or  Ixith.  Conrad  gave  the  matrix  of 
the  form  as  white  hmestone. 

Collections. — Acadezny  of  Natural  Sciences  of  Philadelphia  (1078) ;  Boston  Society  of  Natural 
History. 

Cassidulus  (Ptgorhtnchus)  caeolinensis  TwitcheU,  n.  sp. 

Plate  LXVII,  figures  2a-g. 

Determinative  cJiaracters. — Test  thin  walled,  oval  in  marginal  outline,  posterior  end  trun- 
cated; sides  and  anterior  end  rounded;  upper  surface  convex,  depressed, shghtlj- more  elevated 
posteriorty  than  anteriorty  and  vnth  a  rather  prominent  low,  rounded  ridge  above  the  periproct; 
under  surface  flat,  concave  arovmd  the  peristome;  apex  central  or  slightly  excentric  posteriorly. 
Ambulacral  areas  naiTow.  A  narrow  gi-anulated,  median  band  back  of  the  peristome.  Apical 
system  excentric  anteriorly;  madre])orite  sUglitlj'  tumid.  Peristome  excentric  anteriorly, 
directly  beneath  apical  system,  pentagonal,  with  a  floscelle.  Peri])roct  elliptical,  transverse, 
supramarginal  beneath  an  overhanging  expansion  of  the  test,  whose  edge  is  even  with  the 
posterior  margin. 

Dimensions. — Length  .36  millimeters;  vndth  32  millimeters;  height  IS  millimeters.  This 
specimen  is  about  a  fourth  larger  than  the  average. 

Descnption. — This  species  occurs  in  large  numbei-s  at  several  localities  in  North  Carolma, 
notably  in  association  with  EcMnolampas  appendiculatus.  The  test  is  thin  wailed,  regularly 
oval  in  marginal  outline,  the  posterior  end  vertically  truncated.  The  upper  surface  is  uniformly 
convex,  depressed,  sides  and  anterior  end  rounded,  slightly  more  elevated  posteriorly  than 
anteriorly  and  in  the  form  of  a  low  rounded  ridge  above  the  periproct;  under  surface  flat,  tumid 
near  the  margin,  concave  around  the  peristome.  The  apex  is  central,  or  slightly  excentric 
posteriorly. 


EOCENE   ECHINODEKMATA.  147 

The  ambulacral  areas  are  narrow,  dorsal  portions  petaloid ;  the  petals  long,  rather  narrow, 
nearly  closing,  the  posterior  pair  slightlj^  longer  than  the  others  wdiich  are  nearly  equal  in  length. 
The  poriferous  zones  are  rather  narrow,  faintly  depressed,  outer  pores  oblong,  inner  ones  round, 
pairs  of  pores  conjugate. 

The  surface  of  the  test,  including  the  interjDoriferous  areas  and  the  ridges  Ijetween  the  pairs 
of  i^ores,  is  closely  set  \\'ith  small  imperforate  tul^ercles  set  in  deep  scrobicules.  Between  the 
tubercles  are  minute  granules.  The  tubercles  increase  in  size  on  the  under  surface  except  along 
a  narrow  band  back  of  the  peristome,  which  is  somewhat  smooth  but  dotted  with  numerous 
granulations. 

The  apical  system  is  excentric  anteriorlj".  There  are  four  genital  pores,  the  anterior  pair 
being  nearer  together  than  the  posterior;  and  five  perforated  radial  plates.  The  madreporite  is 
large,  oval  and  faintly  tumid,  as  are  the  adjacent  portions  of  the  interambulacral  areas. 

The  peristojne  is  somewhat  large,  pentagonal,  excentric  anteriorly,  directly  beneath  the 
apical  system,  surrounded  by  a  floscelle  of  which  the  bourrelets  are  rather  prominent,  granu- 
lated, and  together  form  a  nearly  circular  ring  around  the  peristome. 

The  periproctis  elliptical,  transverse,  supramarginal,  at  the  top  of  the  ])osterior  truncation; 
beneath  a  rounded,  transverse,  somewhat  protruding  exiDansion  of  the  test,  whose  edge  is  just 
even  with  the  truncated  posterior  margin. 

Related  forms. — Cassidulus  caroliriensis  is  closely  related  to  C.  conradi  and  resembles  it  in  a 
number  of  features,  notably  in  the  details  of  the  periproct;  but  it  is  to  be  separated  bj^  its  less 
excentric  apical  system,  b_y  its  less  transverse  peristome  with  the  subcircular  ring  of  bourrelets, 
by  being  broader,  more  rounded  and  less  rostrate  posteriorly,  and  hj  having  a  more  marked 
concavity  around  its  peristome.  C.  carolinensis  also  resembles  0.  georgiensis  but  is  to  be  distin- 
guished by  the  concavity  around  its  peristome,  its  less  obtuse  and  less  angular  posterior  margin, 
and  its  lower  and  less  ol^lique  ])03terior  truncation.  Among  European  forms  C.  carolinensis 
greatly  resembles  Pygorhynchus  maveri  De  Loriol  from  the  Tertiary  of  Switzerland  (more  so  than 
does  C.  conradi),  but  differs  iii  having  its  periproct  higher  up  on  the  posterior  surface,  and  in  the 
failure  of  the  expansion  of  the  test  over  the  periproct  to  protrutle  noticeably  beyond  the  j^osterior 
margin.  In  a  number  of  features  0.  carolinensis  is  similar  to  Pygorhynchus  grignonensis 
(Defranco)  Agassiz  from  the  Eocene  of  France,  but  it  can  be  separated  by  its  more  dejiressed 
form  and  the  higher  relative  position  of  its  periijroct. 

Localities. — Smith  Creek  (type),  Rocky  Point,  and  Wilmington,  N.  C. 

Geologic  horizon. — Castle  Hayne  limestone,  upper  Eocene  or  Oligocene. 

Collections. — Johns  Hojikins  University  (T  2004);  U.  S.  National  Museum. 

Cassidulus  amygdala  Desor. 

Cassidulus  amygdala  Desor,  1858,  SjTiopsis  des  (^chinides  fossiles,  p.  Ixv. 
Cassidulus  amygdala  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  22. 
Cassidulus  amygdala  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  22. 

This  is  a  Swiss  species  described  on  page  290  of  Desor's  Synopsis  and  erroneously  listed  by 
Desor  in  his  table  of  distribution,  page  Ixv,  as  among  the  Eocene  Echinodermata  of  America. 
Conrad,  failing  to  note  the  error,  also  listed  the  form  in  his  catalogue  and  check  list. 

Pygorhynchus  rugosus  Ravenel. 

Pygorhynchus  rugosus  Eavenel,  1848,  Ecliinid*,  recent  and  fossil,  of  South  Carolina,  p.  4,  PI.  II,  figs.  7,  8. 
Pygorhynchus  rugosus  Bavenel,  1850,  Cat.  recent  and  fossil  Echinidse,  South  Carolina,  p.  160. 
Pygorhynchus  rugosus  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  91. 

Ravenel,  in  1S4S,  j)ublished  in  an  out  of  the  way  pamphlet  two  ];.(itr  drawings,  imaccom- 
panied  by  a  description,  of  a  form  from  the  Eocene  of  South  Carolina  for  whicli  he  jn-oj/osed 
the  name  Pygorhynchus  rugosus.  The  species  is  not  entitled  to  recognition;  and  the  writer 
has  been  unable  to  locate  the  t.ype  or  to  recognize  the  form  among  the  material  studied. 


148  MESOZOIC    AXD   CEXOZOIC    ECHIXODEEMATA    QF    THE    UNITED    STATES. 

Genus  BBEYNELLA  Gregory. 
Breynella  gregoryi  Twitch  ell,  n.  sp. 
Plate  LXVIII,  figures  la-f. 
Breynella  sp.  Gregory,  1891,  Geol.  Soc.  America  Bull.,  vol.  3,  p.  104.     Nomen  nudum. 

Determinative  characters. — Test  suboval  in  marginal  outline,  broadest  hack  of  the  center, 
narrowing  posteriorly,  truncated  vertically  at  the  posterior  end ;  sides  and  anterior  end  rounded; 
upper  surface  convex,  somewhat  elevated,  especially  along  the  posterior  median  area,  apex 
slightly  to  the  rear  of  the  center;  under  surface  rather  flat,  slightly  concave  near  the  peristome. 
Ambulacral  areas  narrow,  supetaloid;  petals  rather  short,  straight,  flush,  inconspicuous  and 
open  at  the  ends.  Apical  S3'stem  very  excentric  anteriorly.  Peristome  pentagonal,  excentric 
anteriorly,  but  somewhat  less  so  than  the  apical  system;  with  a  floscelle.  Periproct  oblong-oval, 
longitudinal!}^  elongate,  supramarginal,  at  the  top  of,  and  flush  with  the  vertical  stirface  of  the 
posterior  tnmcation. 

Dimension. — ^Length  34  millimeters;  width  28  millimeters;  height  IS  millimeters. 

Description. — Tlais  medium-sized  Breynella  is  the  first  representative  of  the  genus  to  be 
reported  from  the  United  States.  The  specimens  here  described  are  probably  the  same  which 
J.  W.  Gregor}'  saw  at  the  American  Museum  of  Natural  History,  and  as  he  first  recognized  the 
form  as  a  Breynella  it  is  named  in  his  honor.  The  test  of  this  species  is  suboval  to  subovate 
in  marginal  outline,  broadest  back  of  the  center,  narroM-ing  toward  the  posterior  end,  which 
is  vertically  truncated.  The  sides  are  rounded  and  inflated;  the  upper  surface  convex,  some- 
what elevated,  especially  along  the  jjosterior  median  area,  which,  however,  graduaUy  declines  in 
the  form  of  a  low  rounded  ridge  on  approaching  the  region  of  the  periproct;  the  under  sur- 
face rather  flat,  tumid  around  the  margin,  slightly  concave  near  the  peristome.  The  apex  is 
slightly  to  the  rear  of  the  center. 

The  ambidacral  areas  narrow,  widest  at  the  ambitus,  where  they  are  onty  slightly  wider 
than  the  petaloid  portions;  dorsal  portions  subpetaloid,  the  petals  being  rather  short,  straight, 
flush,  inconspicuous,  and  open  at  the  ends;  the  posterior  pair  slightly  longer  than  the  others, 
which  are  nearly  equal  in  length.  The  poriferous  zones  are  rather  narrow;  outer  row  of  pores 
oval,  inner  row  round;  pairs  of  pores  conjugate. 

Tlie  apical  system  is  very  excentric  anteriorly,  being  situated  about  one-third  the  length 
of  the  test  from  the  anterior  end.  Its  details  are  not  weU  sho-wm  on  the  specimens  studied;  but 
there  are  four  genital  pores  of  which  the  anterior  pair  are  nearer  together  than  the  posterior. 

The  peristome  is  pentagonal,  transvereely  elongate,  excentric  anteriorly,  but  somewhat  less 
so  than  the  apical  sj'stem,  with  a  floscelle.  Tlie  flosceUe  is  distmct,  and  the  bourrelets  are  broad 
and  rather  prominent;  but  the  phyllodes  are  not  verj'  conspicuous. 

The  periproct  is  oblong-oval,  longitudinally  elongate,  supramarginal,  at  the  top  of,  and 
nearly  flush  with  the  vertical  surface  of  the  jjosterior  truncation.  A  poorly  defined  shallow 
groove  extends  from  the  periproct  down  the  middle  of  the  posterior  truncation. 

The  sm-face  of  the  test  is  closely  set  with  small  tubercles,  in  deep  scrobicules,  which  are 
somewhat  larger  on  the  under  surface.  There  apjiears  to  be  a  very  narrow,  somewhat  pitted, 
median  band  behind  the  peristome  which  extends  along  close  to  the  zigzag  suture  line. 

Belated  form^. — Breynella  gregoryi  resembles  in  a  general  way  several  of  the  Tertiary  species 
of  Cassidulus;  but  is  readily  separated  b}^  its  longitudinaUy  elongate  periproct.  Its  closest 
American  ally  is  EcJiinanihus  antiUamm  Cotteau,  from  the  Eocene  of  the  West  Indies,  from  which 
it  differs  in  having  its  periproct  overhung  by  an  expansion  of  the  test.  It  resembles  E.  honissenti 
Cotteau,  from  the  Eocene  of  France,  but  is  smaller  and  has  its  apical  sj'stem  more  excentric 
anteriorly.  It  also  closely  resembles  Breynella  equizoata  Gregory,  from  the  lower  Oligocene  of 
Malta,  but  may  be  distinguished  by  its  higher  posterior  margin  and  the  slightly  more  anteriorly 
excentric  position  of  both  its  apical  sA'stem  and  peristome. 

Locality. — ^Santee  Canal,  S.  C. 

Geologic  horizon. — Probably  either  the  Cooper  marl  (upper  Eocene)  or  the  upper  part  of 
the  McBean  formation  (middle  Eocene) . 

Collection. — American  Museum  of  Natural  Historv. 


EOCENE   ECHINODERMATA.  149 

Genus  ECHINOLAMPAS  Gray. 

ECHINOLAMPAS    APPENDICULATUS    EmmonS. 

Plate  LXVIII,  figures  2a-h. 

Eckinolampas  appendiculatus  Emmons,  1858,  Agriculture  Eastern  (bounties:  North  Carolina  Geol.  Survey  Rept.,  p.  307, 

figs.  240,  241. 
Eckinolampas  appendiculatus  Stefanini,  1911,  See.  geol.  italiana  Boll.,  vol.  30,  p.  697. 

Determinative  characters. — Test  suboval  to  subovate  in  marginal  outline,  broad  and  rounded 
anteriorly,  narrowing  in  nearly  straight  lines  to  the  pointed,  obUquely  truncated  posterior  end; 
sides  and  anterior  end  roiinded  and  inflated.  The  upper  surface  convex,  depressed,  and  usually 
rather  flat  on  top,  Avith  a  tumid,  rounded  ridge  over  the  periproct;  under  surface  very  tumid 
for  a  wide  area  around  the  margin,  shghtly  concave  near  the  jieristome.  Apex  central  or  sub- 
central.  Ambulacral  areas  narrow,  dorsal  jDortions  petaloid;  petals  narrow,  some  with  porifer- 
ous zones  unequal  in  length.  Apical  system  excentric  anteriorly.  Peristome  large,  elliptical, 
transverse,  excentric  anteriorly,  with  an  inconspicuous  floscelle.  Periproct  large,  subelliptical, 
inframarginal,  beneath  the  protruding  posterior  ridge. 

Dimensions. — The  figured  form,  which  is  about  average  size,  gave  length  33  millimeters; 
width  28  mUhmeters;  height  17  millimeters.  The  largest  specimen  gave  length  48  miUimeters; 
width  42  miUimeters;  height  23  miUimeters. 

Description. — This  species  was  described  and  figured  by  Emmons  in  1858.  It  appears  to 
be  limited  to  North  Carolina,  where  it  is  often  found  in  association  with  Cassidulus  carolinensis. 
In  actual  nmnber  of  specimens  it  is  the  most  abundant  of  the  Cenozoic  Cassiduloidea  occurring 
in  the  United  States,  the  writer  having  had  more  than  300  specimens  available  for  study.  The 
writer  has  also  had  the  privilege  of  studying  Emmons's  type,  which  is  in  the  collection  of  WilUams 
College;  and  as  a  result  has  determined  that  in  applying  the  name  "appendiculatus"  to  the 
species  based  upon  the''subcordate  sculptured  plate  with  a  pentagonal  opening,  in  the  center  of 
which  there  is  a  pore"  which  was  said  to  occupy  the  apical  disk,  Emmons  made  a  curious  mis- 
take. His  type  does  show  a  plate  of  some  such  character  as  he  described  but  it  is  evidently 
foreign  to  the  test,  probably  a  fragment  of  some  other  fossil — possibly  the  plate  of  some  cidaroid 
form — which  has  by  accident  become  cemented  to  the  test  in  the  neighborhood  of  the  apical 
system.  Emmons's  type  is  the  only  one  of  the  300  specimens  examined  by  the  writer  which 
possesses  any  such  plate.  Furthermore,  it  is  difficult  to  conceive  of  any  possible  function  for 
such  an  appendix  to  an  echinoid  test.  This  species  is  somewhat  variable  in  minor  details,  but 
its  broad  characteristics  are  quite  uniform  and  easily  distinguished.  The  test  is  thin  walled, 
depressed-ovoid  in  general  form;  marginal  outline  suboval  to  subovate,  rounded  anteriorly, 
broadening  back  of  the  middle,  then  rapidly  narrowing  in  almost  straight,  converging  lines  to  the 
rather  pointed,  somewhat  rostrate  posterior  end;  margin  very  round  and  highly  inflated,  less 
so  along  the  narrowing  part  on  both  sides  of  the  posterior  end,  and  dov/nwardly  and  anteriorly 
truncated  at  the  posterior  end.  The  upper  surface  is  usuaUy  rather  low,  regularly  convex, 
depressed,  rather  flat  on  top  and  in  the  form  of  a  tumid  rounded  ridge  over  the  periproct; 
though  occasional  specimens  are  moderately  elevated,  and  somewhat  ridged  along  the  whole 
longitudinal  median  area;  under  surface  very  tumid  for  a  wide  area  around  the  margin, 
slightly  concave  near  the  peristome.     The  apex  is  central  or  subcentral. 

The  ambulacral  areas  are  narrow,  dorsal  portions  petaloid;  petals  narrow,  rather  long, 
varjdng  somewhat  in  details  on  the  same  specimen  and  from  specimen  to  specimen,  the  posterior 
pair  usually  slightly  longer  than  the  anterior  three,  which  are  nearly  equal  in  length,  partly  open 
at  their  extremities.  The  poriferous  zones  are  narrow,  flush,  the  imier  zones  of  the  posterior 
petals  slightly  shorter  than  the  outer  zones,  and  in  a  less  degree  the  anterior  zones  of  the  anterior 
paired  petals  shorter  than  the  posterior  zones;  outer  row  of  pores  oval,  iianer  row  round;  pairs 
of  pores  conjugate,  the  ridges  between  the  pairs  of  pores  prominent  and  ornamented  A\lth  a  row  of 
granules. 

The  surface  of  the  test  is  highly  ornamented.  There  are  numerous  smaU  tubercles  in  wide, 
deep  scrobicules.     On  the  imder  surface  the  scrobicules  are  more  nimierous,  different  in  size  and 


150  MESOZOIC    AXD    CEXOZOIC    ECHIXODEKMATA    OF    THE    UKITED    STATES. 

shape  and  closer  together;  on  the  upper  surface  they  are  more  .scattered  and  hi  gi-anulated  rin^s 
between  which  the  sui-face  is  dotted  with  numerous  small  pits. 

The  apical  system  is  excentric  anteriorly  and  consists  of  four  perforated  basal  plates,  the 
anterior  genital  pores  being  closer  together  than  the  posterior,  five  small  perforated  radial  plates, 
and  a  large,  central,  granulated,  faintly  tumid  madreporite. 

The  peristome  is  rather  large,  regularly  eUiptical,  transverse,  excentric  anteriorly,  though 
slighter  less  so  than  the  apical  system,  surrounded  by  an  inconspicuous  floscelle  with  straioiit 
feeble  phyUodes  and  faintly  defined,  slightly  tumid  bourrelets. 

The  periproct  is  rather  large,  irregularly  elliptical,  the  upper  edge  being  less  convex  than  the 
lower  edge  and  constituting  the  extreme  protruding  posterior  end  of  the  test,  inframarginal, 
beneath  the  overhangmg  rouniled  ridge  of  the  posterior  upper  surface  and  level  with  the  down- 
wardly obhque  trmication  of  the  posterior  margin. 

Related  forms. — Ecliinolampas  appendicidatus  is  not  closely  allied  to  any  other  American 
species.  It  is  easily  distinguished  from  E.  aldrichi,  the  onlj-  other  representative  of  the  genus 
yet  reported  from  the  United  States.  It  resembles  rather  closely  Echinolampas  francei  Desor 
from  the  Eocene  of  France  but  tUffei's  in  being  relatively  broader  and  in  having  a  more  regularly 
elhptical  peristome. 

Localities. — Newbern,  (Emmons),  Eocky  Point  (figured  form),  Smith  Creek,  anil  Wil- 
mington, N.  C. 

Geologic  horizon. — Castle  Haj'ne  limestone,  upper  Eocene  or  OHgocene. 

Collections. — Williams  College;  U.  S.  National  Museum  (138017) ;  Johns  Hopkins  University. 

Suborder   STERNATA. 
Family  SPATANGID.E. 

Genus  HEMIPATAGUS  Desor. 

Hemipatagus  argutus  Clark,  n.  sp. 
Plate  LXIX,  figures  la-d. 

Determinative  characters. — Test  small,  cordiform,  depressed,  highest  just  back  of  posterior 
truncation,  nearly  as  broad  as  long,  nearly  flat  below,  with  broad  anterior  sulcus.  Ambulacra 
nearhr  flush,  ^\'ith  sUghtly  depressed  poriferous  avenues.  Interanibulacra  are  broad,  the  paired 
area  A\dth  several  %\adely  scattered  rather  large,  crenulate  and  perforate  tubercles,  with  deep 
areolas  giving  the  surface  an  irregularly  pitted  appearance.  The  lower  flat  surface  has  many 
tubercles  of  similar  character  especially  on  the  sides  near  the  ambitus.  The  tubercles  are  much 
worn  on  both  the  upper  and  lower  surfaces  of  the  specimen. 

Description. — The  single  specimen  of  this  A-'er}-  beautiful  form  has  a  small  test,  cordiform  in 
outlhie,  somewhat  depressed  and  nearly  as  broad  as  long.  The  upper  surface  is  flattened  ante- 
riorly and  elevated  posteriorly  just  back  of  the  posterior  truncation.  A  broad  anterior  sulcus 
crosses  the  ambitus.     The  lower  surface  is  nearly  flat. 

The  ambulacra  are  nearly  flush,  the  poriferouii  avenues  being  slightly  depressed,  subpetal- 
oidal,  the  anterior  pair  bemg  shorter  than  the  posterior. 

The  interanibulacra  are  broad,  the  paired  areas  with  several  wideh'  scattered  rather  large, 
crenulated  and  jDerforate  tubercles,  vnih.  deep  areolas  giving  the  surface  an  irregularly  pitted 
appearance.  Tlie  lower  flat  surface  has  many  tubercles  of  similar  character  especially  on  the 
sides  near  the  ambitus.  The  tubercles  are  much  worn  on  both  the  upper  and  lower  surfaces  of 
the  specimen. 

The  apical  system  is  mdistinct.  The  peristome  is  large  and  oA-al  in  outline.  The  periproct 
is  large  and  supramarginal  in  position.  - 

Related  forms. — The  species  is  similar  in  certain  features  to. II.  subrostratus  but  is  wider 
anteriorly,  has  a  more  cordate  form,  and  is  higher  posteriorly. 

Locality. — Enterprise,  Clarke  County,  Miss. 

Geologic  horizon. — Claiborne  group,  middle  Eocene. 

Collection. — U.  S.  National  Museum  (141107). 


EOCENE   ECHINODEBMATA.  151 

Hemipatagus  subrosteatus  Clark,  n.  sp. 

Plate  LXIX,  figures  2a-b. 

Determinative  characters. — Test  medium  size,  subcorcliform,  only  slightly  higher  posteriorly, 
longer  than  ^^'ide,  nearly  flat  below,  \nth  broad  anterior  sulcus.  Ambulacra  broad,  somewhat 
depressed,  the  poriferous  avenues  subpetaloidal,  the  anterior  pair  longer  than  the  posterior. 
Interambulacra  mth  a  number  of  large  scattered  tubercles  in  the  paired  areas  ^vith  deep  areolas, 
crenulate  and  perforate. 

Dimensions. — Length  33  millimeters;  width  29  millimeters;  height  14  millimeters. 

Description. — ^The  single  specimen  of  this  species  is  much  damaged  on  the  lower  surface 
and  posterior  end,  neither  the  peristome  nor  perip roc t  being  preserved.  The  testis  of  medium 
size,  subcordiform,  only  slightly  higher  on  the  posterior  j^art  than  on  the  forward  part  of  the 
upper  surface.  It  is  longer  than  vnde,  the  widest  portion  being  onlj^  slightly  forward  of  the 
middle  of  the  test.  A  broad  anterior  sulcus  extends  from  the  apex  over  the  ambitus.  The 
lower  surface  is  nearly  flat. 

The  ambulacra  are  nearly  flush,  somewhat  depressed,  the  poriferous  avenues  subpetaloidal, 
the  anterior  pair  longer  than  the  posterior.  The  pores  are  oval  and  comiected  by  prominent 
furrows. 

The  interambulacra  are  somewhat  elevated  with  a  number  of  large,  scattered  tubercles  in 
the  paired  areas.     The  tubercles  have  deep  areolas,  and  are  crenulate  and  perforate. 

Related  forms. — ^This  species  is  similar  to  H.  argutus  but  is  narrower  anteriorly,  has  a  less 
cordate  form,  and  is  lower  posteriorly. 

Locality. — Wilmington,  N.  C. 

Geologic  horizon. — <]!astle  Hayne  limestone,  upper  Eocene  or  Oligocene. 

Collection. — ^U.  S.  National  Museum  (164652). 

Genus  SCHIZ ASTER  Agassiz. 

SCHizASTEK  LECONTEi  Merrlam. 

Plate  LXIX,  figures  3a-b. 

Schizaster  (?)  sp.  Merriam,  1S97,  Jour.  Geology,  vol.  5,  p.  773. 

Schizaster  Iccontei  Merriam,  1809,  California  Acad.  Sci.  Proc,  3d  ser.,  Geology,  vol.  1,  pp.  164,  l(i5,  PL  XX,  figs.  1,  la. 

Schizaster  lecontei  Stefanini,  1911,  Soc.  Geol.  italianaBoll.,  vol.  30,  p.  697. 

Determinative  characters. — ^Test  smaU,  cordiform,  elevated,  -svith  a  sharj:)  ridge  from  apical 
system  to  posterior  truncation.     Apex  jjosterior  to  center  of  test.     Ambulacra  broad,  dej^ressed, 
petals  of  posterior  pair  less  than  half  the  length  of  anterior.     Peripetalous  fasciole  distinct.  • 
Apical  system  posterior  to  center.     Peristome  well  forward.     Periproct  high  on   truncated 
posterior  surface. 

Dimensions. — Length  20  to  23  millimeters. 

Description. — ^The  specimens  of  this  species  are  preserved  only  as  impressions  or  casts, 
badly  crushed.  The  test  is  small,  cordiform,  upper  surface  much  elevated,  with  a  sharp  ridge 
running  from  the  apical  system  to  the  posterior  truncated  surface.  A  broad  groove  notches 
the  anterior  margin. 

The  ambulacra  are  broad,  the  poriferous  zones  depressed,  petaloidal,  the  petals  of  the 
posterior  pair  very  short,  less  than  half  the  length  of  the  anterior,  sometimes  almost  circular  in 
outline.     Pores  elongated,  apparently  yoked. 

The  interambulacra  broad.  Tubercles  larger  on  the  lower  surface.  Peripetalous  fasciole 
quite  distinct  on  one  specimen.  Traces  of  what  appears  to  be  the  lateral  fasciole  have  been 
seen  beneath  the  periproct. 

Apical  system  excentric,  posterior,  anterior  to  the  summit. 

Peristome  well  forward,  broad  two-lipped.     Periproct  high  up  on  the  triuicated  posterior  end. 


152  MESOZOIC    AXD   CEXOZOIC    ECHIXODEKMATA    OF    THE    UNITED    STATES. 

Meniam  says:  " Numerous  large  spines  much  like  those  of  Scliizaster  hare  been  found  at 
one  locality,  but  if  they  belong  to  this  genus  at  all  they  were  probably  derived  from  another  and 
much  larger  species." 

Locality. — Contra  Costa  County,  Cal. 

Geologic  Jionzon. — Martinez  and  Tejon  formations,  Eocene. 

Collection. — ^University  of  California.  i 

ScHiZASTEK  AEMiGEE  Clark,  n.  sp. 
Plate  LXX,  figures  la-d. 

Determinative  characters. — Test  rather  large,  cordiform,  depressed  upper  surface  slopes  at 
first  rapidly  then  more  slowly  from  anterior  margin  to  apical  system,  beyond  which  an  elevated 
sharp  ridge  continues  to  the  truncated  posterior  margin.  Ambulacra  in  broad  deep  furrows, 
the  paired  ambulacra  in  moderately  sunken  petals,  the  anterolateral  being  about  one  and  one- 
half  times  as  long  as  the  posterolateral.     Peripetalous  and  lateral  fascioles  distinct. 

Dimensions. — Length  53  millimeters;  vndth  46  millimetei-s ;  height  22  millimeters. 

Descnption. — Tliis  species  has  a  test  of  moderately  large  size,  much  depressed  and  clearly 
cordiform  in  marginal  outline.  The  upper  surface  slopes  at  first  rapidly  from  a  sharp  anterior 
margin  to  near  the  apical  system  when  it  becomes  nearly  flat  for  a  short  distance.  Beyond 
the  apical  system  a  sharp  elevated  ridge  highest  near  the  middle  point  continuous  on  to  the 
truncated  posterior  margin. 

The  ambulacra  are  broad,  the  single  anterior  ambulacrum  being  situated  in  a  deep  broad 
groove  that  deeply  indents  the  anterior  margin.  The  paired  ambidacra  have  broad  deep  petals, 
the  anterolateral  being  somewhat  over  one  and  a  half  times  as  long  as  the  posterolateral. 

The  interambulacra  are  more  or  less  fiat,  slightly  gibbous,  the  posterior  much  elevated 
forming  a  sharp  ridge.  The  sm-face  is  thickly  covered  with  small  perforate  tubercles.  The 
peripetalous  and  lateral  fascioles  are  very  distinct. 

The  peristome  is  near  the  anterior  margin  in  a  shallow  depression.  The  periproct  is  high 
on  truncated  posterior  margin. 

Locality. — Cocoa  post  office,  Choctaw  County,  Ala. 

Geologic  hoHzon.—St.  Stephens  limestone  Gower  part),  upper  Eocene. 

Collection. — ^U.  S.  National  Museum  (141104). 

SCHIZASTER   sp. 
Plate  LXX,  figure  2. 
Fragment  of  spatangoid  test,  Clark,  1901,  Maryland  Geol.  Siu^ey,  Eocene,  p.  232,  PI.  LXI,  fig.  1. 

Description. — ^A  fragment  of  a  spatangoid  test  found  among  the  Eocene  materials  collected 
at  Evergreen,  Va.,  apparently  belongs  to  the  genus  Schizaster,  to  which  it  is  here  referred.  A 
portion  of  an  ambulacrum  with  the  adjacent  portion  of  an  interambulacrum,  showing  many 
characteristic  features,  is  preserved.  The  ambidacrum,  probably  one  of  the  anterolateral  pair, 
is  petaloidal,  the  petal  sunken  and  rather  narrow.  The  interambulacrum  is  somewhat  gibbous 
and  has  preserved  a  part  of  a  peripetalous  fasciole. 

Locality. — Evergreen,  Va. 

Geologic  horizon. — Nanjemoy  formation,  middle  Eocene. 

Collection. — Johns  Hopkins  University  (T  2001). 

Genus  LINTHIA  Merian. 

LiNTHIA    WILMINGTONENSIS    Clark,  U.  Sp. 

Plate  LXX,  figures  3a-c. 

Determinative  characters. — Test  large,  cordiform,  gibbous  above,  nearly  flat  below,  ambu- 
lacra wide,  anterior  in  deep  groove,  anterolateral  with  petals  in  long  deep  grooves,  postero- 
lateral wiih  petals  about  one-half  the  length  of  the  anterolateral  and  also  deeply  sunken.     Inter- 


EOCENE   ECHINODEEMATA.  153 

ambulacra  wide,  prominent,  and  covered  witli  numerous  small  tubercles.     Peristome  in  promi- 
nent depression. 

Dimensions. — Length  56  millimeters;  width  55  millimeters;  height  34  millimeters. 

Description. — This  relatively  large  form  has  an  elevated,  gibbous  upper  surface  and  a  nearly 
flat  lower  surface  except  for  the  peristome  dejiression.  It  is  cordiform  in  marginal  outline 
about  as  wide  as  long  and  rounded  laterally. 

The  ambulacra  are  wide,  the  single  anterior  ambulacrum  being  situated  in  a  deep  groove, 
which  deeply  indents  the  margin.  The  anterolateral  paired  ambulacra  have  long,  broad  sunken 
petals,  while  those  of  the  posterolateral  pair  are  only  about  half  as  long. 

The  interambulacral  plates  are  covered  mth  small  perforated  tubercles.     The  peripetalous  and 
lateral  fascicles  can  be  readily  traced. 

The  peristome  is  in  a  pronounced  depression  near  the  anterior  margin.  The  periproct  is  not 
shown  on  the  type  form. 

Locality. — Wilmington,  N.  C. 

Geologic  horizon. — Castle  Hayne  limestone,  upper  Eocene  or  Oligocene. 

Collection. — U.  S.  National  Museum  (1664S2). 

LlNTHIA    ALABAMEXSIS    Clark,  U.  sp. 
Plate  LXXI,  figures  la-d,  2a-d. 

Determinative  clmracters. — Test  small,  nearly  round,  except  for  groove  on  anterior  margin  and 
slight  truncation  posteriorly,  low,  somewhat  depressed,  the  upper  surface  sloping  gradually 
toward  the  apex.  Ambulacra  narrow,  not  deeply  sunken,  the  posterolateral  petals  much  shorter 
than  the  anterolateral.  Peristome  near  anterior  margin.  Periproct  relatively  high  on  narrow 
truncated  posterior  margin. 

Dimensions. — Large  specimen:  Length  34  millimeters;  width  35  miUimeters;  height  19 
millimeters.  Small  specimen:  Length  22  millimeters;  v^ddth  22  millimeters;  height  14  milli- 
meters. 

Description. — The  test  of  tliis  species  is  small,  low,  somewhat  depressed,  nearly  round  in 
ambital  outline,  except  for  the  rather  shallow  groove  on  the  anterior  margin  and  the  sUght,  nar- 
row truncation  on  the  posterior  margin.  The  upper  surface  slopes  gradually  from  the  anterior 
margin  posteriorly. 

The  ambulacra  are  narrow  and  not  deeply  sunken.  The  single  anterior  ambulacrum  is 
situated  in  a  narrow,  rather  shallow  groove.  The  anterolateral  paired  ambulacra  have  long, 
narrow,  rather  shallow  petals,  and  the  posterolateral  pair  are  short  and  shallow. 

The  interambulacral  plates  are  covered  with  small  perforate  tubercles.  The  peripetalous 
and  lateral  fascioles  are  not  easily  traced. 

The  peristome  is  in  a  shallow  depression  near  the  anterior  margin.  The  periproct  is  situated 
relatively  liigh  on  the  narrow  truncated  posterior  margin. 

Localities. — Prairie  Creek,  Wilcox  County,  Ala. ;  near  Grand  Glaise,  Jackson  Count}',  Ark. 

Geologic  horizon. — Midway  group,  lower  Eocene. 

Collection.— U .  S.  National  Museum  (166483,  173371). 

Genus  ETTPATAGtTS  Agassiz. 

EUPATAGUS   CAROLIXENSIS  Clark,  n.  sp. 

Plate  LXXI,  figures  3a-d,  4. 

Determinative  characters. — Test  medium  size,  oval,  moderately  tumid,  ncai'ly  flat  along  the 
median  line,  mth  slight  keel.  Ambulacra  depressed,  anterior  very  shghtly,  paired  ambulacra 
in  shallow  grooves,  long,  the  anterolateral  pair  shorter  than  the  posterolateral.  Interambulacra 
shghtly  tumid.     Apical  system  excentric,  well  forward.     Peristome  excentric  in  front. 

Dimensions. — Length  48  millimeters;  width  39  milUmeters;  height  22  mUlimeters. 

Description. — This  very  beautiful  form  has  a  test  of  moderate  size,  oval,  moderately  tumid 
on  the  upper  surface  and  sloping  up  at  a  low  angle  along  the  median  line  toward  the  posterior 


154  MESOZOIC    AXD    CEXOZOIC    ECHIXODEEMATA    OF    THE    UNITED    STATES. 

ridge,  which  is  low.  The  posterior  margin  is  sUghtly  contracted.  The  lower  surface  is  nearly 
flat,  with  a  slight  posterior  keel. 

The  ambulacra  are  broad,  the  anterior  ambulacrum  occupying  a  slight  depression  and  the 
paired  ambulacra  sUght  grooves  in  the  petaloidal  portions.  The  petals  are  long,  the  postero- 
lateral being  longer  than  the  anterolateral.  The  pore  pairs  are  rather  large  and  coimected  by 
furrows. 

The  interambulacra  are  sUghtly  tunaid,  the  tubercles  on  the  lower  surface  being  much  larger 
than  on  the  upper  surface. 

The  apical  sj^stem  is  small  and  situated  well  forward.  The  peristome  is  large,  semilunar 
in  shape,  and  excentric  in  front.     The  peripetalous  fasciole  is  clearly  defuied. 

Locality. — Wilmington,  N.  C. 

Geologic  horizon. — Castle  Hayne  limestone,  upper  Eocene  or  Ohgocene. 

Collection. — U.  S.  National  Museum  (164674,  166484). 

Genus  BBISSOPSIS  Agassiz. 

Bkissopsis  eimulatus  Ravenel. 

Brissopsis  rimulatus  Ravenel,  1848,  EctinoidEe,  recent  and  fossil,  of  South  Carolina,  p.  4,  PI.  II,  figs.  3  and  4. 
Brissopsis  rimulatus  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 
Brissopsis  rimulatus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  708. 

Description. — Ravenel  did  not  describe  this  s})ecies  in  1848  when  he  proposed  the  name, 
biit  he  published  two  very  distinctive  figures,  which  should  be  sufficient  to  identify  the  form  if 
material  representing  the  species  should  be  found.  No  such  material  was  at  hand  when  this 
monograph  was  under  preparation. 

Locality. — South  Carolina  (Ravenel). 

Geologic  horizon. — Eocene  (?). 

Collection. — Unknown . 

Genus  MACROPNETJSTES  Agassiz. 

ilACROPNEUSTES  CAROLiNEXsis  Clark,  n.  sp. 

Plate  LXXI,  figures  5ar-d. 

Determinative  cJiaracters. — Test  small,  elevated,  tumid,  subpentagonal.  Apical  system 
excentric  forward.  Ambulacra  narrow,  petaloidal  portions  in  narrow,  shallow  grooves.  Surface 
of  plates  covered  with  numerous  tubercles.  Peristome  about  one-third  the  distance  from  the 
anterior  to  the  posterior  margin. 

Dimcnsiotis. — Length  28  millimeters;  width  27  milUmeters;  height  22  nulhmeters. 

Description. — This  attractive  little  form  has  an  elevated  test,  tumid  in  form,  and  subpentag- 
onal in  ambital  outline.  The  apex  is  excentric  forward.  The  margin  is  rounded.  The  ambulacra 
are  narrow,  the  petaloidal  portions  being  elongate  in  narrow,  shallow  grooves.  The  petals  are 
imperfectly  closed.  The  surface  of  the  plates  is  covered  with  numerous,  irregularly  dispersed 
granules.  The  peristome  is  large,  excentric,  situated  about  one-third  of  the  distance  from  the 
anterior  to  the  posterior  margin ;  irregularly  dispersed  tubercles.  The  interambulacra  are  slightly 
gibbous  above,  the  margin  sharp,  and  the  lower  surface  nearly  flat.  The  fascicles  axe  rather 
indistinct. 

The  peristome  is  large,  semilunar,  with  large  projecting  posterior  labrum.  The  periproct 
is  large  and  low  on  the  imperfectly  truncated  posterior  surface. 

Locality. — Wilmington,  N.  C. 

Geologic  horizon. — Castle  Hayne  limestone,  upper  Eocene  or  Ohgocene. 

Collection. — U.  S.  National  Museum  (1646.51). 


EOCENE   ECHINODEKMATA.  155 

Maceopneustes  MORTON!  (Conrad). 

Plate  LXXII,  figures  la-d. 

EoJnsler  mortoni  Conrad,  1850,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  2,  p.  40,  PI.  1,  fig.  10. 

HoJasler  mortoni  Boyle.  l.'^9.3,  IT.  S.  Geol.  Survey  Dull.  102,  p.  150. 

Macro pneusles  mortoni  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  700. 

Determinative  characters. — Test  large,  elevated,  tumid,  slightly  cordiform,  nearly  round, 
apex  excentric  forward.  Amljulacra  broad,  petaloidal  portions  elongate,  in  very  shallow 
depressions,  nearly  flush.  Surface  of  both  ambulacra!  and  interambulacral  plates  outside  the 
petals  covered  with  numerous  irregularly  dispersed  tubercles.  Peristome  forward  about  one- 
third  the  distance  from  the  anterior  to  the  posterior  margin.  Periproct  large,  short  distance 
aljovo  margin. 

Dimensions. — Length  84  millimeters;  width  86  millimeters;  height  52  millimeters. 

Description. — The  test  of  the  species  is  large,  elevated,  and  tumid.  It  is  slightly  cordi- 
foi-m  in  ambital  outline,  nearly  round  but  for  the  slight  anterior  groove  and  the  ill-defined 
posterior  truncation.  The  apical  system  is  excentric  forward,  the  high  upper  sm-face  giving 
the  test  a  somewhat  subconical  form. 

The  ambulacra  are  broad,  the  petaloidal  portions  elongate,  nearly  flush  in  very  shallow 
depi'essions  that  reach  far  down  the  sloping  sides. 

The  petals  of  the  ambulacra  outside  the  petaloidal  portions  of  the  ambulacra  and  the 
inter  ambulacra  are  covered  with  numerous  irregularly  dispersed  tubercles. 

The  peristome  is  large,  excentric  forward,  situated  about  one-thud  of  the  distance  from 
the  anterior  to  the  posterior  margin.  The  periproct  is  large  and  situated  a  short  distance 
above  the  margin. 

Localities.- — Palmyra,  Lee  Comity,  Ga.  (type) ;  Fail,  Choctaw  County,  Ala.  (figured  specimen) . 

Geologic  liorizon. — -Jackson  formation  (upper  Eocene)  and  Vicksburg  formation  (lower 
Oligocene). 

Collection.— \].  S.  National  Museum  (146468). 

Genus  SARSELLA  Pomel. 
Saesella  gregoryi  Clark,  n.  sp. 

Plate  LXXII,  figures  2a-d. 
Sarsella  sp.  Gregory,  1892. 

Determinative  characters. — 'Test  small,  cordiform,  depressed.  Apical  system  nearly  cen- 
tral. Ambulacra  very  diverse  anterior  in  broad  deep  group,  petaloidal  portions  of  paired 
ambulacra  slightly  sunken,  the  posterolateral  more  than  the  anterolateral.  Several  large, 
irregularly  dispersed  tubercles  crenulate  and  perforate  on  the  interambulacra.  Peristome 
semilunar.     Periproct  high  on  posterior  trmication. 

Dimensions. — Length  IS. .5  millimeters;  width  17.5  millimeters;  height  9  millimeters. 

Description.—  Tliis  small  form  was  noted  by  Gregory  in  his  cursory  examination  of  Ameri- 
can echinoids  when  in  America  in  1891  and  was  referred  to  the  genus  Sarsella.  The  tost  is 
small  cordiform  in  ambital  outline,  depressed,  only  slightly  higher  on  the  posterior  portion 
of  the  upper  surface  than  the  anterior.     The  under  surface  is  nearly  flat. 

The  ambulacra  are  very  diverse.  The  anterior  ambulacrum  is  situated  in  a  broad  deep 
groove.  The  paired  ambulacra  have  diverse  slightly  sunken  pt^taloidal  areas,  the  petals  of  the 
posterolateral  pair  being  broader  and  shorter  and  closed  below  while  those  of  the  anterolateral 
pair  are  only  imperfectly  closed. 

The  surface  of  the  interambulacral  plates  bears  a  number  of  irregularly  dispersed  large 
crenulate  and  perforate  tubercles.     They  are  confined  to  the  paired  interambulacra. 

The  apical  system  is  small.  The  perforations  in  the  four  genitals  are  distinct  on  the  type 
specimen. 


156  MESOZOIC   AND   CENOZOIC    ECHINODEBMATA    OF    THE    UNITED    STATES. 

The  peristome  is  large,  semilunar,  and  distinctly  excentric  forward.  The  periproct  is 
large,  high  on  the  posterior  truncation. 

Locality. —  Santee  Canal,  S.  C. 

Geologic  horizon. —  Santee  marl  member  of  McBean  formation,  of  Claiborne  group,  middle 
Eocene. 

Collection. —  American  Museum  of  Natural  History. 

Spatangus?  pachecoensis  (Pack). 

Spatangm  f  pachecoensis  Pack,  1909,  Univ.  Califdmia  Dept.  Geology  Bull.,  vol.  5,  No.  18,  p.  276,  PL  XXIII,  figs.  4,  5. 
Spatangus  f  pachecoensis  Lambert,  1910,  Rev.  crit.  pali^ozoologie,  4"  anii^e,  No.  1,  p.  55. 
Spatangiis  f  pachecoensis  Stefamni,  1911,  Soc.  geol.  italiaua  Boll.,  vol.  30,  p.  705. 

Description. —  The  species  was  established  by  Pack  on  casts  of  poorly  preserved  fragments. 
It  apparently  belongs  to  the  Spatangidse,  but  its  generic  relations  can  not  be  determined. 
Lambert,  on  the  other  hand,  positively  refers  it  to  the  Scutellidse  and  considers  the  material 
too  fragmentary  for  specific  description. 

Locality.— "Northwest  of  Pacheco,  Contra  Costa  County,  Cal. 

Geologic  horizon.—  Tejon  formation,  upper  Eocene. 

Collection. —  University  of  California. 


OLIGOCENE   ECHINODERMATA. 
Class  ECmNOIDEA. 
Subclass  REGULARIA  ENDOBRANC'HIATA. 
Order  CIDAROIDEA. 

FamUy  CIDARID.«. 

Genus  CIDARIS  Leske. 

CiDARis  MORTONI  Conrad. 

Plate  LXXIII,  figure  1. 

Cidaris  mortoni  Conrad,  1S50,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  2,  p.  40,  PL  I,  fig.  13. 

?  Cidaris  sp.  Bouve,  1S51,  Boston  Soc.  Nat.  History  Proc,  vol.  4,  p.  3. 

Cidaris  mortoni  Cotteau,  1S92,  Paleontologie  frangaise,  fichinides  ^ocfenes,  p.  449. 

Cidaris  mortoni,  Stefanini,  1911,  Soc.  geol.  italiaua  Boll.,  vol.  30,  p.  698. 

Description. — The  fragment  of  a  Cidaris  test,  wHch  is  here  figured  and  referred  to  Cidaris 
mortoni,  has  all  of  the  essential  characteristics  of  the  form  figured  and  briefly  described  by 
Conrad.  The  species  is  large,  globose,  and  circular  in  ambital  outline.  The  ambulacra  are 
straight,  the  pore  openings  round  and  somewhat  distinct.  The  interambulacra  are  composed 
of  large  plates,  each  bearing  a  large  perforate  and  apparently  uncrenulate  tubercle. 

Localities. — Near  Palmj-ra,  Lee  County,  Ga.  (type):  Baker  County,  Ga.  (figured  specimen). 

Geologic  horizon. — Vicksburg  formation,  lower  Oligocene. 

Collection. — Boston  Society  of  Natural  History  (1555). 

Cidaris  smithi  Clark,  n.  sp. 
Plate  LXXIII,  figures  2a-c,  3. 

Determinative  characters. — Test  medium  size,  moderateh^  tall,  subcircular  in  ambital  out- 
line. Ambulacra  narrow,  slightly  flcxuous.  Interambulacra  broad,  each  with  two  rows  of 
primary  tubercles  perforate  and  crenulate,  the  areola  surrounded  by  a  row  of  secondarj^  tuber- 
cles.    Mihary  space  small. 

Dimensions. — Diameter  35  milUmeters;  height  24  millimeters. 

Description. — The  test  of  this  species  is  of  medium  size,  moderately  tall,  and  subcircular 
in  ambital  outline. 

The  ambulacra  are  narrow,  slightl}^  flexuous,  the  poriferous  zones  separated  by  four  rows 
of  granules  at  the  ambitus,  which  become  reduced  to  two  rows  both  above  and  below. 

The  interambulacra  are  \nde,  rather  more  than  three  times  the  width  of  the  ambulacra. 
Each  plate  bears  a  large  primar}^  tubercle  which  is  perforate  and  crenulate  and  has  a  medium- 
sized  areola  surrounded  by  a  row  of  granules.  The  relatively  narrow  miliar^'  space  is  thicldy 
covered  with  tubercles. 

A  large  tubercle  was  found  with  the  test  that  probably  belongs  to  the  same  species.  Cer- 
tain Cidaris  spines  found  at  the  Central  Salt  Works,  Clarke  County,  Ala.,  may  represent  the 
same  species. 

Locality. — The  Rocks,  Clarke  Count}',  Ala. 

Geologic  horizon. — St.  Stephens  limestone  (upper  portion),  lower  Ohgocenc. 

Collection. — Alabama  Geological  Survey. 

39800°— 15 11  157 


158  MESOZOIC   ASD   CENOZOIC    ECHINODEKMATA    OF    THE    UNITED    STATES. 

Ctdaeis  georgiana  Clark,  n.  sp. 
Plate  LXXIII,  figure  4. 

Determinative  characters. — Test  moderately  high,  subcii'cular,  medium  size.  Ambulacra 
wide,  with  large  primary  tubercle  on  each  plate,  the  tubercles  on  contiguous  plates  closely 
approximate,  wide  miliary  space  between  the  rows  of  tubercles. 

Dimensions. — Diameter  38  (0  millimeters;  height  25  (?)  millimeters. 

Description. — The  test  of  this  species  is  only  partly  preserved.  It  shows,  however,  the 
chief  determinative  characters.  It  is  evidently  unlike  any  other  form  hitherto  described. 
The  test  is  of  medium  size,  moderately  high,  and  subcircular  in  ambital  outline.  The  full 
height  and  diameter  can  not  be  with  certainty  determined.  The  ambulacra  are  rather  broad 
and  straight,  with  four  rows  of  granules  between  the  poriferous  zones. 

Locality. — Muckafoonee  Creek,  Ga. 

Geologic  lionzon. — Vicksburg  formation,  lower  Ohgocene. 

Collection. — U.  S.  National  Museum  (166485).' 

CiDARis  branneri  Arnold. 
Plate  LXXIII,  figure  5. 

Cidaris  branneri,  Arnold,  1903,  U.  S.  Nat.  Mus.  Proc,  vol.  29,  pp.  363,  364,  PI.  XXXIII.  fig.  5. 
Cidaris  branneri  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  698. 

Description. — Arnold  says : 

Test  unknown.  Spines,  long,  slender,  circular  in  cross  section,  attaining  a  length  of  at  least  25  millimeters  and  a 
diameter  of  over  2  millimeters.  .Surface  of  spine  smooth  for  about  one-fifth  its  length  from  the  base;  above  this  it  is 
ornamented  by  ten  longitudinal  rows  of  elongated  nodes  or  granules  which  are  liarely  connected  near  the  smooth 
portion,  but  which  partake  more  and  more  of  the  character  of  nodose  ribs  toward  the  distal  end;  the  last  one-fifth  of  the 
spine  is  ornamented  liy  fi\e  prominent,  slightly  nodose  riljs;  the  extreme  end  is  blunt  and  rounded;  collar  at  base  only 
faintly  developed. 

The  spines  of  this  species  are  easily  distinguishable  from  those  of  C.  merriami,  new  species,  from  the  Eocene,  by 
their  smaller  size,  fewer  but  much  more  prominently  nodose  longitudinal  ribs,  and  smooth  basal  portion.  No  complete 
spine  of  C.  merriami  was  obtained,  so  that  the  smooth  basal  section  may  possibly  be  a  characteristic  of  this  latter  species 
as  well  as  of   C.  branneri. 

Dimensions. — Length  20  milUmeters;  diameter,  basal  end  2.2  millimeters,  distal  end  1.1 
millimeters. 

Localities. — Santa  Cruz  quadrangle,  Santa  Cruz  County,  locahty  No.  109  on  Bear  Creek,  4 
miles  above  its  confluence  with  the  San  Lorenzo  River,  Cal. 

Geologic  horizon. — San  Lorenzo  formation,  upper  Ohgocene. 

Collection. — U.  S.  National  Museum  (1056). 

Subclass  REGULARIA  ECTOBRANCHIATA. 

Order  BIADEMOIDEA. 

Suborder  ARBACINA. 

Family  ARBACIID.E. 

Genus  CCELOPLEUKUS  Agassiz. 

C(ELOPLEURi;s  ALDRiCHi  Clark,  n.  sp. 

Plate  LXXIII,  figures  6a-b,  7a-c. 

Determinative  characters. — Test  large,  subpentagonal,  tumid  at  ambitus,  depressed  above, 
nearly  flat  below.  Ambulacra  narrow,  the  two  rows  of  primary  tubercles  becoming  ver}^  small 
toward  the  apex;  poriferous  zones  narrow  and  straight,  the  pore  pairs  uniserial.  Interam- 
bulacra  -wide,  each  with  several  rows  of  large  primary  tubercles  at  ambitus  reduced  to  two 
around  peristome  and  on  upper  surface,  leaving  wide  median  area  above.  Tubercles  with  flat 
areolas  and  large  imperforate  mamelons.     Peristome  with  very  slight  brancliial  incisions. 


OLIGOCENE   ECHINODEEMATA.  159 

Dimensions. — Specimen  A:  Diameter  38  millimeters;  height  20  millimeters.  Specimen  B: 
Diameter  2S  millimeters;  height  12  millimeters. 

Description. — The  species  is  characterized  by  a  rather  large  test,  with  subpentagonal  out- 
line. It  is  tumid  at  the  ambitus  and  depressed  on  the  upper  surface.  It  is  nearly  fiat  below. 
The  ambulacra  are  narrow,  each  bearing  two  rows  of  primary  tubercles  that  diminish  rapidly 
in  size  from  the  ambitus  toward  the  apex.  The  poriferous  zones  are  narrow,  the  pore  pairs 
being  uniserial  and  somewhat  crowded  toward  the  apex.  The  interambulacra  are  ^\\Ae  with 
several  rows  of  primary  tubercles  at  the  ambitus  which  become  reduced. to  two  toward  the  peri- 
stome and  above  the  ambitus,  where  a  broad  median  area  devoid  of  tubercles  occurs.  The 
peristome  is  small  with  slight  branchial  incisions. 

The  several  specimens  examined  are  much  broken  and  the  surfaces  much  worn. 

Locality. — Perdue  Hill,  Ala. 

Geologic  horizon. — St.  Stephens  limestone  (upper  portion),  lower  Oligocene. 

Collection. — U.  S.  National  Museum  (T.  H.  Aldrich). 

Suborder  DIADEMINA. 
Family  CYPHOSOMATID^. 

Genus  GAGARIA  Diifican. 

Gagaria  AMERICANA  Clark,  n.  sp. 

Plate  LXXIII,  figures  8a-b. 

Determinative  characters. — Test  small,  circular,  tumid,  subhemispherical,  concave  below. 
Ambulacra  narrow,  each  with  two  rows  of  small  primary  tubercles,  perforate  and  crenulate; 
each  compound  plate  with  three  pairs  of  pores.  Interambulacra  wide,  each  with  two  rows  of 
primary  tubercles.     Apical  system  large,  flush. 

Dimensions. — Diameter  14  millimetere ;  height  8  millimeters. 

Description. — This  beautiful  form  has  a  very  small  test,  with  a  circular  ambital  outline. 
It  is  tumid,  subhemispherical,  rather  depressed  above,  concave  below.  The  ambulacra  are 
narrow,  each  area  provided  with  two  rows  of  perforate  and  crenulate  primary  tubercles  which 
are  longest  at  the  ambitus  and  reach  to  the  apical  system,  gradually  diminishing  in  size.  The 
poriferous  zones  are  narrow,  the  pore  pairs  being  three  in  number  on  each  compound  plate. 
The  interambulacra  are  broad,  each  carrying  two  rows  of  primary  tubercles  similar  to  the  ambu- 
lacra between  wliich  are  many  small  secondaries  and  granules.  The  apical  system  is  large  and 
flush. 

This  species  is  based  on  a  single  specimen,  the  peristomial  region  of  which  is  much  damaged. 

Locality. — The  Rocks,  Clarke  County,  Ala. 

Geologic  horizon. — St.  Stephens  hmestone  (upper  portion),  lower  OUgocene. 

Collection. — U.  S.  National  Museum  (T.  H.  Aldrich). 

Suborder  ECHININA. 
Family  TRIPLECHINID.«. 

Genus  ECHINUS  Litine. 

Echinus  ?  sp. 
Echinus  sp.  Cunningham,  1895,  Am.  Micr.  Jour.,  vol.  16,  pp.  193-196,  figs. 

Description. — Small  spines  and  fi-agments  of  plates  are  figured  by  Cumiingham  from  "cal- 
careous marl"  in  Clarke  County,  Miss.,  and  referred  to  the  genus  Echinus.  It  is  cjuite  impossible 
to  determine  definitely  the  generic  relations  of  these  forms. 

Locality. — Red  Bluff  station,  Chickasawhay  River,  Clarke  County,  Miss. 

Geologic  horizon. — Vicksburg  limestone,  lower  Oligocene 

Collection. — K.  M.  Cunningham,  Mobile,  Ala. 


160  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA    OF    THE    UNITED    STATES. 

Subclass  IRREGULARIA. 

Older  GNATHOSTOMATA. 

Suborder  CLYPEASTRINA. 

Family  FIBULARIID^. 

Genus  ECHINOCYAMUS  Phelsum. 

EcHiNOCYAMUs  VAUGHANi  Twitchell,  n.  sp. 

Plate  LXXIV,  figures  la-d. 

DetermirMtive  characters. — Test  very  small,  though  larger  than  related  American  species, 
thick  walled,  almost  regularly  egg  shaped,  though  elongated  longitudinally,  about  t-wice  as  long 
as  broad.  Upper  sm-face  elevated,  both  upper  and  lower  surfaces  flattened  along  the  longi- 
tudinal median  areas.  Apical  system  anteriorly  excentric,  with  four  medium-sized  genital 
pores.  Petals  relatively  short  and  potaloidal  area  smaller  than  in  related  forms.  Peristome 
relatively  large,  central,  slightly  depressed;  periproct  very  small,  close  to  peristome. 

Dimensions. — Length,  8  millimeters;  width,  4  millimeters;  height,  4  millimeters. 

Description. — This  species  is  founded  upon  a  specimen  collected  in  Georgia  by  T.  Wayland 
Vaughan,  of  the  United  States  Geological  Survey,  in  whose  honor  it  is  named.  The  test, 
though  actually  very  small,  is  larger  than  in  the  other  American  representatives  of  the  genus. 
The  test  is  thick  walled,  elongate  egg  shaped  in  general  form,  elongate  subelliptical  to  elongate 
subovate  in  marginal  outline,  somewhat  pointed  anteriorly,  about  twice  as  long  as  broad.  The 
upper  surface  is  high  (the  height  of  the  test  equalling  the  breadth)  and  flattened  longitudinally; 
mider  surface  also'flattened  somewhat  along  the  longitudinal  median  area  and  slightly  concave 
around  the  peristome. 

The  ambulacral  petals  are  rather  well  defined,  relatively  short,  thus  making  the  petaloidal 
area  relatively  smaller  than  in  allied  American  forms;  petals  wide  open  at  ends;  poriferous  zones 
diverge  in  almost  straight  lines  to  the  ends  and  consist  of  small  round  pores  in  pairs  not  dis- 
tinctly conjugated. 

The  peristome  is  relatively  large,  central,  slightly  depressed  below  the  surface;  periproct 
very  small,  about  one-third  the  diameter  of  the  peristome  and  very  close  to  the  peristome. 

Related  forms. — E.  vaughani  is  most  closely  related  to  E.  texanus  but  can  be  readily  sepa- 
rated by  its  larger  size,  less  oval  marginal  outline,  more  pointed  anterior  end,  greater  difference 
between  its  longitudinal  and  transverse  diameters,  and  smaller  petaloidal  area.  E.  vaughani 
also  resembles  E.  parvus  and  E.  huxleyanus  but  differs  from  both  in  having  its  periproct  near 
the  peristome.     It  also  differs  from  E.  huxleyanus  in  being  less  fragile  and  less  depressed. 

Locality. — Little  Horseshoe  Bend,  Flint  River,  Ga. 

Geologic  horizon. — ^Vicksburg  formation,  lower  Oligocene. 

Collection.— U.  S.  National  Museum  (1664S6). 

Family  LAGANID^. 
Genus  LAGANUM  Blainville. 

Laganum  eldridgei  Twitchell,  n.  sp. 

Plate  LXXIV,  figures  2a-d. 

Determinative  characters. — Test  large,  subpentagonal  to  subdccagonal  in  marginal  outline, 
longitudinally  elongate,  truncated  at  the  anterior  and  posterior  ends,  more  or' less  undulating 
along  the  sides.  Whole  form  greatly  depressed,  margin  thin  but  thicker  than  slightly  concave 
submarginal  area,  petaloidal  region  tumid.  Apex  and  apical  system  subcentral.  Lower  surface 
flat.  Ambulacral  petals  long,  elongate  elliptical,  extending  two-thu-ds  the  way  to  the  margin, 
pointed  and  closed  at  the  ends;  pairs  of  pores  conjugated  by  very  narrow  more  or  less  wavy 
grooves.  Ambulacral  areas  very  wide  at  margin,  narrowing  rapidly  to  ends  of  petals.  Peri- 
stome  moderate   in  size,   subcentral,   subpentagonal   to   subelliptical,    transversely  elongate. 


EOCENE   ECHINODEBMATA.  161 

Ambulacral  groovos  apparently  simple  and  straight,  each  groove  having  a  fine  line  on  both 
sides  which  rapidly  diverge  from  the  main  groove.  Periproct  relatively  large,  suboval,  longi- 
tudinally elongate,  one-fourth  the  way  from  the  margin  to  the  peristome. 

Dimensions.—  Length  9G  millimeters;  width  75  millimeters;  height  10  millimeters. 

Description.—  The  only  specimens  kno%vn  of  this  large  and  handsome  Laganum,  the  largest 
representative  of  the  genus  from  American  deposits,  were  collected  in  Florida  by  the  late 
G.  IT.  Eldridge  of  the  United  Stat«es  Geological  Survey  and  the  species  is  therefore  named  in 
his  honor.  The  tc^st  is  large,  being  3  to  4  inches  long  and  2i  to  3  inches  wide.  In  marginal 
outline,  it  is  subpentagonal  to  decagonal,  decidedly  longer  than  broad;  margin  thin  but  thicker 
than  the  submarginal  area,  truncated  at  anterior  and  posterior  ends,  more  or  less  undulating 
along  the  sides.  The  whole  form  is  greatly  depressed,  the  upper  surface  slightly  concave  around 
the  submarginal  area,  arising  centrally  in  the  form  of  a  low  mound  which  involves  the  whole 
petaloidal  area;  apex  subcenti'al;  lower  surface  flat. 

The  ambulacral  areas  are  very  wide  at  the  margin,  being  there  about  four  times  the  width 
of  the  interambulacral  areas,  narrowing  rapidly  to  near  the  ends  of  the  petals.  The  petals  are 
long,  elliptical  in  outline,  extending  two-thirds  the  way  to  the  margin,  pointed  and  closed  at 
the  ends.  The  anterior  pair  shorter  than  the  other  three,  which  are  subequal  in  length.  The 
poriferous  zones  are  wide,  more  than  half  the  width  of  the  rather  narrow  interporiferous  areas, 
inner  row  of  pores  elliptical,  outer  row  veiy  narrowly  slitlikc,  hardly  discernible,  pairs  of  pores 
conjugated  by  very  narrow  more  or  less  wavy  grooves. 

The  interambulacral  areas  are  very  narrow  at  the  margin,  widen  rather  rapidly  to  near 
the  ends  of  the  petals,  and  narrow  again  toward  the  apical  region.  The  whole  test  is  closely 
set  with  very  small  tubercles,  among  which  are  scattered  at  irregular  distances  some  larger  ones 
in  deep  scrobicules. 

The  apical  system  is  subcentral,  at  the  summit  of  the  tumid  area.  There  are  four  largo 
genital  pores,  of  which  the  anterior  pair  are  set  closer  together  than  the  posterior  nair.  No 
other  details  could  be  made  out  on  the  specimens. 

The  peristome  is  of  moderate  size,  subcentral,  slightly  to  the  rear  of  the  apical  system, 
subpentagonal  to  subelliptical,  transversely  elongate.  The  details  of  the  ambulacral  grooves 
could  not  bo  made  out  satisfactorily  on  the  specimens  studied.  As  they  leave  the  peristome 
there  appears  to  be  a  single  straight  groove  on  each  side  of  which  are  two  fuie  lines  which  rapidly 
diverge  from  the  main  groove.  These  side  lines  may  be  the  boundary  linos  of  what  on  better 
preserved  specimens  would  prove  to  be  finely  granulated  areas,  thus  forming  a  peristomial  star. 

The  periproct  is  relatively  large,  about  half  the  size  of  the  peristome,  suboval,  longitudinally 
elongate,  situated  about  one-fourth  the  way  from  the  margin  to  the  peristome. 

Related  forms. —  L.  eldridgei  is  readily  distinguished  from  all  other  American  forms.  It 
closely  resembles  L.  elongatum  Agassiz,'  whose  origin  is  unkno\vn  and  which  is  not  even  stated 
to  be  fossil,  being  very  similar  in  size,  general  form,  and  marginal  outline,  but  differs  from  it 
in  having  a  suboval  instead  of  circular  periproct,  placed  a  little  farther  from  the  posterior  margiii. 

Locality. —  Suwanee  River,  Fla. 

Geologic  horizon. — Vicksburg  group,  lower  Oligoceno. 

Collection.— U.  S.  National  Museum  (1(34683). 

Laganum  archerensis  Twitchell,  n.  sp. 
Plate  LXXV,  figures  la-d. 
Determinative  characters. — Test  small,  subpentagonal  to  subdecagonal  in  marginal  outline. 
General  form  subdiscoidal,  upper  surface  very  low,  nearly  parallel  with  lower  surface,  with  a 
slightly  concave  ring  involving  most  of  ambulacral  petals  between  the  faintly  tumid  apical 
region  and  the  notably  thickened  margin.  Highest  part  of  test  along  anterior  margin.  Lower 
surface  flat.  Ambulacral  petals  subelliptical,  extending  two-thirds  the  way  to  the  margin, 
ends  closed.  Apical  system  slightly  excentric  anteriorly,  with  four  genital  poi'cs  set  unusiuilly 
far  apart.     Peristome  small,  pentagonal,  central;  ambulacral  grooves  simple,  straight  lines 

1  Monographies  dVchinodermes  vivans  et  fossiles,  vol.  2,  Des  scutelles,  pp.  117-118,  Fl.  XXIV,  figs.  1-2. 


162  MESOZOIC   AKD   CEXOZOIC    ECHIXODEEMATA    OF    THE   UNITED    STATES. 

flanked  by  finely  granulated  areas,  tlie  five  constituting  a  peristomial  star.  Periproct  small, 
transversely  suboval,  about  one-fourth  the  way  from  margin  to  peristome. 

Dimensions. — ^Length  18  millimeters;  mdth  16  millimeters;  heiglit  .3.5  millimeters. 

Description. — Only  a  single  specimen  of  this  new  Laganum  has  been  discovered.  It  was 
found  at  Archer,  Fla.,  whence  the  name  here  given.  Tlie  test  is  small,  subpentagonal  or  sub- 
decagonal  in  marginal  outline.  The  whole  form  is  greatly  depressed;  subdiscoidal,  the  upper 
surface  being  practically  parallel  with  the  lower;  the  apical  region  faintly  tumid,  the  area 
between  the  apical  region  and  the  margin  slightly  concave;  the  margm  notably  thickened, 
slightly  less  so  posteriorly  than  anteriorly.  The  lower  surface  is  flat.  The  highest  part  of  the 
test  is  along  the  surface  of  the  anterior  margin,  from  whence  the  upper  surface  slopes  gently 
to  the  posterior  margin,  the  central  tumidity  being  hardly  any  higher  than  the  side  margins. 

The  ambulacral  petals  are  subeUiptical,  extending  about  two-tliirds  the  way  to  the  margm, 
the  larger  part  of  each  petal  being  depressed  so  as  to  form  a  part  of  the  concave  ring  on  the 
upper  surface,  the  ends  of  the  petals  practically  closed.  The  poriferous  zones  are  rather  wide, 
about  half  as  wide  as  the  interporiferous  areas,  the  proximal  ends  poorly  defined,  the  imier 
row  of  pores  round,  the  outer  row  slitlike,  the  pairs  of  pores  conjugated. 

The  interambulacral  areas  are  vei-y  narrow,  especially  at  the  margin,  where  they  are  hardly 
more  than  one-third  as  mde  as  the  ambulacral  areas.  The  whole  surface  of  the  test,  including 
the  interporiferous  areas  and  apical  region,  is  covered  with  small  tubercles  set  in  deep  scrobicules, 
which  are  larger  on  the  under  surface. 

The  apical  system  is  sliglitly  excentric  anteriorly  at  the  summit  of  the  faintly  tumid  central 
area.  There  are  four  large  genital  pores,  set  unusually  far  apart,  the  anterior  pair  being  nearer 
together  than  the  posterior  pair.  The  poriferous  zones  could  not  be  seen  to  come  together  at 
the  proximal  ends,  and  the  perforations  in  the  radial  plates  could  not  be  discerned  on  the 
specimen. 

The  pei'istome  is  small,  central,  pentagonal.  The  ambulacral  grooves  each  consist  of  a 
central  impressed  line  and  two  narrow  areas  of  fine  granulation  which  are  bounded  by  faint 
lines;  these  gi'ooves  are  quite  distinct  for  a  short  distance  from  the  peristome,  thus  constituting 
a  well-defined  peristomial  star,  they  then  become  gradually  less  distmct,  so  that  as  the  margin  is 
approached  they  can  hardly  be  discerned. 

The  periproct  is  small,  about  half  the  diameter  of  the  peristome,  transversely  suboval, 
about  one-fourth  the  way  from  the  margin  to  the  peristome. 

Related  forms. — L.  archerensis  is  most  closely  related  to  L.  dalli,  but  can  be  easily  dis- 
tinguished by  the  concave  ring  on  its  upper  surface,  by  its  narrower  petals,  its  less  depressed 
and  narrower  poriferous  zones,  and  by  having  its  periproct  closer  to  the  margin.  It  is  also 
allied  to  L.  Jloridanum,  but  has  a  less  regularly  oval  marginal  outline  and  a  larger  petaloidal 
area.  It  diffei's  from  L.  crustuloides  in  being  lower  centrally,  in  having  a  concave  ring  on  its 
upper  surface,  and  in  having  a  flat  lower  surface. 

Locality. — ^Archer,  Fla. 

Geologic  horizon. — Vicksburg  group,  lower  Oligocene. 

Collection. — U.  S.  National  Museum  (164667a). 

Laganum  johnsoni  Twitchell,  n.  sp. 
Plate  LXXV,  figures  2a-d. 

Description  and  determinative  characters. — The  test  of  this  new  Laganum  is  moderate  in 
size  and  almost  regularly  oval  in  marginal  outline.  The  upper  surface  is  moderately  elevated 
centrally,  the  height  being  about  one-third  of  the  width,  the  tumid  area  extending  to  the  ends 
of  the  petals;  the  submarginal  area  about  equal  in  thickness  to  the  margin,  wMch  is  slightly 
undulating,  very  thick,  liigh  and  rounded,  tliicker  and  liigher  than  in  related  forms,  slightly 
thinner  at  the  middle  of  the  posterior  end  than  elsewhere.  The  lower  surface  is  decidedly 
concave,  the  concavity  reaching  nearly  to  the  margin  and  near  the  peristome  being  about 
equal  to  one-half  the  height  of  the  test.     The  apex  is  subcentral.      Tlie  posterior  petals  are 


OLIGOCENE   ECHINODEEMATA.  163 

lanceolate,  the  anterior  three  subelliptical,  all  of  them  pomted  and  closed  at  the  ends,  extendmg 
two-thirds  or  more  of  the  way  to  the  margin,  the  anterior  paii-  slightly  shorter  than  the  rest. 
The  poriferous  zones  are  very  narrow,  much  narrower  than  the  slightly  tumid  interporiferous 
areas,  sometimes  irregular,  inner  ends  poorly  defined,  imier  row  of  pores  round,  outer  row 
slitlike,  pairs  of  pores  conjugated.  The  whole  surface  of  the  test  is  covered  %vith  rather  con- 
spicuous small  tubercles  which  are  larger  on  the  lower  surface.  The  apical  system  is  sub- 
central,  with  four  large  genital  pores.  The  peristome  is  small,  subpentagonal,  subcentral; 
ambulacral  grooves  poorly  defined,  not  well  preserved  on  the  specimen.  The  periproct  is 
small,  subcircular  to  subpentagonal,  about  one-third  the  way  from  the  margin  to  the  peristome. 

Dimensions. — Length  34  millimeters;  -i^-idth  30  millimeters;  height  10  m.illimeters. 

Related  forms. — ^This  species  is  very  closely  related  to  L.  crustuloides,  in  fact  so  close  that 
further  collecting  may  lead  to  its  being  made  a  synonym  of  the  latter  species.  Its  chief  dis- 
tinguishing features  are  its  greater  height  and  the  greater  height  and  thickness  of  its  margin. 
These  features  distmguish  it  not  only  from  L.  crustuloides,  but  also  from  the  other  American 
representatives  of  the  genus,  from  which  it  differs  also  in  its  pronouncedly  concave  lower  surface. 

Locality. — Turks  Cave,  Ala. 

Geologic  horizon. — Probably  Vicksburg  formation,  lower  Oligocene. 

Collection. — ^U.  S.  National  Museum  (137202);  collected  hj  L.  C.  Johnson,  after  whom  it  is 
named. 

Lagaxum  floridanum  Tw-itchell,  n.  sp. 
Plate  LXXV,  figures  3a-d. 

Determinative  characters. — Test  small,  oval  in  marginal  outline.  General  form  subdiscoidal, 
the  upper  surface  very  low,  almost  parallel  with  the  lower  surface,  -with  a  slightly  concave  ring 
between  the  slightly  tumid  petaloidal  area  and  the  notably  thickened  margin.  Apex  and 
apical  system  slightly  excentric  anteriorly.  Lower  surface  flat.  Ambulacral  petals  subelliptical, 
very  short,  extending  halfway  to  the  margin,  pointed  and  closed  at  ends.  Petaloidal  area  notably 
smaller  than  in  related  forms.  Periproct  small,  circular,  about  one-third  the  way  from  margin 
to  peristome. 

Dimensions. — Length  20  millimeters;  mdth  18  millimeters;  height  3  millimeters. 

Description. — This  new  Laganum  from  Florida  has  a  small  test  which  is  almost  regidarly 
oval  in  marginal  outline.  The  whole  form  is  greatly  depressed;  subdiscoidal;  the  upper  sur- 
face being  almost  parallel  Avith  the  lower;  the  apical  region  slightly  tumid,  the  tumidity  involv- 
ing the  larger  part  of  the  petals;  the  region  around  the  ends  of  the  petals  concave;  the  margin 
notably  thickened,  slightlj^  more  so  anteriorly  than  posteiiorly.  The  lower  surface  is  flat,  or 
nearly  so.  The  apex  is  slightly  excentric  anteriorly,  at  the  summit  of  the  central  tumid  area, 
which  rises  but  very  slightly  above  the  height  of  the  margin. 

The  ambulacral  petals  are  subelliptical,  somewhat  pointed  and  closed  at  the  ends;  very 
short,  extending  only  about  halfway  to  the  margin,  subequal  in  length.  The  poriferous  zones  are 
very  narrow,  much  narrower  than  the  interporiferous  areas,  the  proximal  ends  poorly  defined, 
inner  row  of  pores  round,  outer  row  slitlike,  pairs  of  pores  conjugated.  The  whole  surface  of 
the  test  is  covered  \dth  small  tubercles  set  in  deep  scrobicules,  which  are  somewhat  larger  on 
the  lower  surface. 

The  apical  system  is  slightly  excentric  anteriorly,  coincident  with  the  apex.  There  are 
four  large  genital  pores,  the  anterior  pair  being  set  closer  together  than  the  posterior  pair. 
The  poriferous  zones  can  not  be  seen  to  come  together  at  their  proximal  ends,  and  the  perfora- 
tions of  the  radial  plates  can  not  be  made  out. 

The  peristome  is  small,  slightly  excentric  anteriorly,  subpentagonal.  The  ambulacral 
grooves  are  inconspicuous  and  could  not  be  made  out  on  the  single  specimen  studied. 

The  periproct  is  small,  about  half  the  diameter  of  the  jieristome,  circular,  hicated  about 
one-third  the  way  from  the  margin  to  the  peristome. 

Related  forms. — L.floridanwm  is  closely  related  to  L.  airherensis  and  tv  L.  crustuloides,  but 
differs  from  both  in  being  more  regularlv  oval  in  marginal  outline  and  in  having  a  smaller 


164  MESOZOIC    Als^D   CENOZOIC    ECHINODEEMATA   OF    THE    UNITED   STATES. 

petaloidal  area.     It  differs  further  from  L.  crustuloules  in  having  a  flat  under  surface,  a  less 
elevated  central  area,  and  a  concave  ring  on  the  upper  surface. 

Locality. — Johnsons  Sink,  Fla. 

Geologic.  Jionzon. — ^Vicksburg  group,  lower  Oligocene. 

Collection.— JJ .  S.  National  Museum  (137SS4). 

Laganum  dalli  Twitchell,  n.  sp. 

Plate  LXXV,  figures  4a-d. 

Determinative  cJiaraciers. — Test  small,  subpentagonal  in  marginal  outline.  General  form 
subdiscoidal,  the  upper  surface  very  low,  almost  parallel  with  the  flat  lower  surface.  Apex 
and  apical  system  slightly  excentric  anteriorly.  Ambulacral  petals  broad,  subovate,  extending 
two-thirds  the  way  to  the  margin;  poriferous  zones  mde,  depressed  below  the  general  surface, 
thus  making  the  narrow  interporiferous  areas  stand  out  in  relief;  madreporite  tumid.  Peri- 
stome probably  subcentral.  Periproct  small,  circular,  about  midway  between  margin  and 
peristome. 

Dimensions.— 'Length  16  millimeters;  width  15  millimeters;  height  4.5  millimeters. 

Description. — The  type  of  this  handsome  little  Laganum  was  found  at  Archer,  Fla.,  by 
W.  H.  Dall  of  the  United  States  National  iluseum,  ia  whose  honor  the  species  is  named.  This 
species  occurs  in  association  with  Laganum  arcJierensis.  The  test  is  small  in  size  and  subpen- 
tagonal in  marginal  outline.  The  whole  form  is  greatly  depressed,  subdiscoidal,  the  upper 
surface  being  almost  i^arallel  vnih  the  lower.  The  margin  is  notablj^  thickened,  slightly  less  so 
at  the  middle  of  the  posterior  end.  The  lower  surface  is  flat  or  nearly  so.  The  apex  is  subcentral 
or  very  slightly  excentric  anteriorly,  though  it  is  but  slightly  higher  than  the  margin  of  the  test. 
There  is  no  distinct  concave  ring  on  the  upper  surface,  but  the  poriferous  zones  of  the  ambu- 
lacral petals  are  slightly  depressed  below  the  general  surface. 

The  ambulacral  petals  are  subovate  in  outline,  broad,  extending  nearly  two-thirds  the  way  to 
the  margin,  rounded,  blunt,  and  closed  at  the  ends.  The  poriferous  zones  are  very  wide,  as 
wide  as  the  interporiferous  areas,  slightly  depressed  below  the  general  surface;  toner  row  of 
pores  rotmd,  outer  row  slitlike,  pairs  of  pores  conjugated  by  very  narrow  grooves.  Inter- 
poriferous areas  narrow,  standkig  in  relief  by  reason  of  the  depression  of  the  poriferous  zones. 
The  whole  surface  of  the  test,  including  the  interporiferous  areas,  is  covered  with  small  tubercles, 
set  in  deep  scrobicules,  which  are  larger  on  the  under  surface. 

The  apical  system  is  subcentral  or  slightly  excentric  anteriorly,  coincident  with  the  apex. 
There  are  four  large  genital  pores  of  which  the  anterior  pair  are  nearer  together  than  the 
posterior  pair.     The  madreporite  is  tumid.     No  other  details  can  be  made  out. 

The  imder  surface  is  damaged  on  the  single  specimen  known  and  the  details  ia  regard  to 
the  peristome  and  ambulacral  grooves  can  not  be  given,  though  it  is  evident  that  the  peristome 
was  central  or  subcentral  in  position. 

The  periproct  is  small,  circular,  about  midway  between  the  margin  and  the  peristome. 

Related  forms. — L.  dalli  is  most  closely  related  to  L.  archerensis,  differing  chiefly  in  having 
no  concave  ring  on  the  upper  surface  and  in  having  its  periproct  farther  from  its  margin. 

L.  dalli  closely  resembles  Sismondia  antillarum  Cotteau  from  the  Eocene  of  the  island  of 
St.  Barthelemy  but  is  distiaguished  by  being  thicker  as  a  whole,  esi^ecially  on  the  borders. 

Locality. — Archer,  Fla. 

Geologic  Jionzon. — Vicksburg  group,  lower  Oligocene. 

Collection. — ^U.  S.  National  Museum  (164667b). 


OLIGOCENE   ECHINODEEMATA.  165 

Order  ATELOSTOMATA. 

Suborder  ASTERNATA. 

Family  NUCLEOLITIDiE. 

Genus  AMBLYPYGUS  Agassiz. 

Amblypygus  merrilli  T^v^tchell,  n.  sp. 

Plate  LXXVI,  figures  la-d;  Plate  LXXVII,  figures  la-b,  2a-b;  Plate  LXXVIII,  figures  la-b. 

Determinative  characters. — Test  large  to  very  large,  subhemisplierical  to  depressed  sub- 
conical;  cii-cular  or  subcircular  in  marginal  outline;  sides  rounded;  under  surface  concave.  Apex 
central  or  subcentral.  Ambulacral  areas  tumid,  broad,  widest  between  apex  and  ambitus; 
petals  wide  open,  nearly  reaching  the  ambitus,  poriferous  zones  wide,  slightly  depressed.  Peri- 
stome large,  irregidarly  subtriangidar,  oblique,  slightly  excentric  anteriorly.  Periproct  very 
large,  larger  than  the  peristome,  subelliptical  to  subpyriform,  longest  longitudinally,  about 
midway  between  peristome  and  posterior  margin. 

Dimensions. — Specimen  A  (type):  Length  115.5  millimeters;  width  114  millimeters;  height 
62  miUimeters.    Specimen  B :  Length  73  millimeters ;  width  69  millimeters;  height  40  millimeters. 

Description. — This  superb  Amblypygus,  which  is  one  of  the  largest  of  American  ecliinoids, 
is  the  first  representative  of  this  rather  rare  genus  to  be  reported  from  the  United  States.  The 
type  specimen  was  collected  by  G.  P.  Merrill,  of  the  United  States  National  Museum,  and 
the  species  is  therefore  named  in  his  honor.  The  test  of  the  present  species  is  large  to  very 
large,  ranging  from  about  70  milUmeters  to  ai)out  115  millimeters  in  diameter.  It  is  sub- 
hemispherical  to  depressed  subcorneal  in  form,  the  upper  surface  decUning  immediately  and 
equally  on  all  sides  from  the  central  or  subcentral  apex;  circular  or  subcircular  in  marginal 
outline.     The  margin  is  rounded  and  inflated;  the  under  surface  concave  centrally. 

The  ambulacral  areas  are  broad,  widest  about  midway  between  apex  and  ambitus,  thence 
narrowing  to  the  apex  and  peristome;  they  are  slightly  tumid,  thus  forming  five  tumid  ridges 
from  apex  to  peristome.  The  dorsal  portions  of  the  areas  are  subpetaloid,  the  petals  being 
long,  about  reaching  the  ambitus,  wide  open  at  their  extremities.  The  poriferous  zones  are 
wide,  slightly  depressed;  both  outer  and  inner  rows  of  pores  round,  pairs  of  pores  conjugated  by 
long,  narrow  grooves. 

The  interambulacral  areas  are  broad.  The  surface  of  the  whole  test,  including  the  inter- 
poriferous  areas,  is  covered  with  numerous  small  perforate  tubercles,  with  sunken  scrobicules. 

The  apical  system  is  large,  central  or  subcentral.  Most  of  the  area  of  the  system  is  occu- 
pied by  the  large,  slightly  tumid,  granulated  madreporite,  which  appears  to  be  the  enlarged 
right  anterior  basal  plate.  There  are  four  large  genital  pores,  the  two  anterior  being  nearer 
together  than  the  posterior  pair.  The  i-adial  plates  and  their  perforations  can  not  be  discerned 
on  the  specimen. 

The  peristome  is  very  large,  irregularly  subpyriform,  slightly  excentric  anteriorly.  It  is 
placed  in  an  oblique  position,  its  longest  diameter  being  about  30°  to  the  transverse  axis  of  the 
test. 

The  periproct  is  very  large,  larger  than  the  peristome,  subelliptical  to  subpyriform,  situated 
about  halfway  between  the  peristome  and  posterior  margin,  though  slightly  nearer  the  peri- 
stome; its  longer  diameter  extending  longitudinally. 

Related  forms. — AmUyfygus  inerrilli  is  not  closely  related  to  any  other  echinoid  from  the 
United  States.  Of  foreign  forms  it  resembles  both  A.  americanus  ]\Iichelin  from  the  Tertiary  of 
Jamaica '  and  A.  alius  Duncan  and  Sladen  f  i-om  the  Tertiary  of  India,  being  intermediate  between 
them  in  relative  height.  The  proportion  of  the  mean  diameter  to  the  height  in  A.  merrilli  is 
1:55,  whereas  in  the  Jamaican  form,  according  to  Duncan  and  Sladen,  it  is  1:409  and  in  the 

1  The  only  good  description  of  A.  americanus  Michelin  is  given  l>y  Duncan  and  Sladen  in  The  Tertiary  Echinoidca  of  Kachh  and  Kattywar, 
p.  13,  which  contains  additions  to  Desor's  descrij,  Jon  liased  on  a  specimen  in  the  British  Museum.  So  far  as  the  \\Titer  has  been  able  to  ascertain 
the  form  has  never  been  figured. 


166  MESOZOIC   AND   CEXOZOIC    ECHINODEEilATA    OF    THE    UNITED    STATES. 

Indian  1:0.62  or  1:0.63.  A.  merrUli  also  differs  from  ^1.  a/<«,s  in  having  its  peristome  more 
angular  and  less  oblique  and  its  periproct  more  pointed  posteriorly  and  farther  from  the  pos- 
terior margin.  It  is  nearer  A.  americanus  but  is  less  depressed  and  has  a  more  subcorneal  upper 
surface. 

Localities. — Kendrick  lime  quarries  near  Ocala,  Marion  County  (type),  and  Clarke,  Alachua 
County,  Fla. 

Geologic  Tionzon. — Ocala  limestone  of  Yicksburg  group,  lower  OUgocene. 

Collection.— \J .  S.  National  Museum  (164934,  A;   137S70,  B). 

Genus  OLIGOPYGUS  De  Loriol  (amended). 

Oligopygus  was  founded  in  1SS7  by  De  Loriol  on  the  species  OJujopygus  uietTierbiji  from 
the  Tertiary  of  Florida  and  so  far  as  known  has  few  representatives  outside  of  the  United 
States.  De  Loriol  possessed  but  a  few  specimens  and,  although  his  diagnosis  is  well  drawn, 
the  large  number  of  specimens  studied  by  the  -WTiter  (over  sixty)  has  shown  the  necessity  of 
amending  the  description  of  the  genus  in  a  number  of  important  particulars,  of  which  the  most 
important  is  noting  the  fact  that  it  includes  forms  in  wliicli  the  periproct  is  inframarginal. 

Test  moderately  large,  with  tliick  walls,  especially  at  the  ends;  usually  oval,  may  be 
subcircular,  or  subpent agonal;  sides  tumid;  under  surface  sUghtly  concave,  with  a  deep,  trans- 
verse depression  around  the  peristome;  upper  surface  convex,  more  or  less  depressed;  apex 
central  or  anteriorly  excentric. 

Apical  system  central  or  subcentral,  compact,  small,  with  four  perforated  basal  plates;  the 
five  radial  plates  small,  with  minute  pores;  madreporite  central,  tumid,  extending  to  or  between 
the  posterior  radial  plates. 

Ambulacral  areas  broadest  at  the  ambitus,  the  anterior  paired  areas  curving  posteriorly 
near  the  peristome;  faintly  tumid  on  the  upper  surface;  dorsal  portions  varying  from  sub- 
petaloid  to  petaloid,  the  petals  differing  slightly  in  length  and  more  or  less  open,  otherwise 
similar.  Poriferous  zones  broad;  pores  equal  or  nearly  so,  pairs  united  by  a  long  groove. 
Beyond  the  petaloid  portions  to  and  beyond  the  ambitus  each  plate  is  perforated  at  its  outer 
end  by  two  or  three  pairs  of  very  small  pores. 

Peristome  central,  or  subcentral,  peiitagoiial,  slightly  elongate  transversely,  at  the  bottom 
of  the  transverse  depression  in  the  under  surface;  floscelle  and  jaws  wanting.  Periproct  very 
small,  circular,  openmg  on  the  inferior  face  between  the  peristome  and  the  postei'ior  margin; 
may  be  inframarginal.  Tubercles  small,  equal,  more  or  less  scattered,  surrounded  by  deep 
scrobicules  and  imperforate. 

Oligopygus  wethekbyi  De  Loriol. 

Plate  LXXVIII,  figures  2a-d,  3a-b. 

Oligopygus  welherbyi  De  Loriol,  1S87,  Ret-ueil  zool.  Suisse,  vol.  4,  No.  3,  pp.  396-398,  PI.  XVII.  figs.  7-8. 

Oligopygus  wetherbyi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  70.5. 

Oligopygus  wetherbyi  Stefauini,  1911,  Bevista  itaUana  di  paleontologia,  vol.  17,  pt.  2,  p.  11. 

Determinative  cMracters. — Test  with  tliick  walls,  oval,  sides  tumid,  upper  surface  depressed 
and  rather  flat  on  top;  under  surface  mth  a  very  deep,  long,  flarhig,  transvei-se  depression  around 
the  peristome.  Ambulacral  areas  wide  at  the  ambitus;  doi-sal  portions  petaloid,  constric- 
tions at  the  ends  of  the  petals  somewhat  pronounced.  Apex  and  apical  system  central  or 
subcentral.  Peristome  pentagonal,  opening  at  the  bottom  of  the  depression  in  the  under  sur- 
face. Periproct  very  small,  circular,  situated  about  midway  between  the  peristome  and  pos- 
terior margin. 

Dimensions. — Specimen  A:  Length  34  millimeters;  width  29  millimeters;  height  16  milli- 
meters. 

Description. — The  ^^Titer  has  not  had  the  opportunity  of  seeing  the  type  of  this  species, 
but  De  Loriol's  full  and  clear  description  and  excellent  drawmgs  have  permitted  its  ready  iden- 
tification among  the  material  studied.     The  test  is  unusually  tliick,  especially  at  the  ends; 


OLIGOCENE   ECHIKODEKMATA.  167 

quite  regularly  oval  in  marginal  outline,  though  sometimes  narrowing  anteriorly;  margin  rounded 
and  inflated,  the  anterior  end  somewhat  more  so  than  the  posterior,  giving  that  end  a  bulging 
appearance  forward.  The  upper  surface  is  uniformly  convex;  but  depressed  and  rather  flat  on 
top;  under  surface  slightly  concave  near  the  middle  and  Avith  a  very  deep,  transverse  depression 
around  the  peristome.     The  apex  is  subcentral,  or  slightly  forward  of  the  center. 

The  ambulacral  areas  are  ^vide  at  the  ambitus  from  which  they  narrow  to  the  peristome 
and  apex,  but  with  somewhat  pronounced  constrictions  at  the  ends  of  the  petaloid  portions; 
the  anterior  paired  ambulacra  curving  posteriorly  on  approacliing  the  peristomial  depression ; 
dorsal  portions  petaloid,  the  odd  petal  being  longer  than  the  others,  which  are  equal  or  nearly 
equal  in  length.  The  poriferous  zones  are  broad,  more  than  half  the  \vidth  of  the  interporiferous 
area,  moderately  aj)art  at  their  extremities;  the  pores  equal  or  nearly  so,  small,  elliptical;  pairs 
of  pores  united  l)y  long,  narrow,  oblique  grooves.  Beyond  the  petaloid  portions  the  small 
narrow  plates  of  those  portions  give  place  to  broad  plates,  each  of  which  to  and  beyond  the 
ambitus  has  two  or  three  pairs  of  very  small  round  pores  placed  obliquely  near  together  at 
the  extreme  outer  ends  of  the  plates.  The  interporiferous  areas  are  shghtly  tumid  and  stand 
out  in  reUef . 

The  apical  system  is  central  or  subcentral.  The  madreporite  is  large  and  tumid,  central, 
pentagonal,  the  posterior  edge  being  straight  and  coincidmg  with  those  of  the  posterior  radial 
plates.  There  are  four  genital  pores  situated  at  the  edge  of  the  madreporite,  the  posterior  pair 
being  farther  apart  than  the  anterior;  and  there  are  five  small  subtriangular  radial  plates,  each 
perforated  by  a  very  small  pore. 

The  peristome  is  pentagonal,  slightly  elongated  transversely,  opening  at  the  bottom  of  a  very 
deep,  long,  flaring  transverse  depression  in  the  middle  of  the  under  surface.  The  size  and  shape 
of  this  depression  varies,  but  its  length  at  the  surface  is  usually  about  one-half  the  width,  and 
its  depth  about  one-half  the  height  of  the  test.  Its  anterior  and  posterior  walls  slope  at 
nearly  the  same  angle  but  in  opposite  directions  toward  the  peristome  forming  a  broad,  deep, 
V-shaped  conca-\nty. 

The  periproct  is  very  small  and  circular,  and  situated  at  about  midway  between  the 
peristome  and  the  posterior  margin. 

Numerous  small,  uniform,  imperforate  tubercules,  surrounded  by  deep  scrobicules,  are 
scattered  irregularly  over  the  entire  surface  of  the  test. 

Related  forms. — Oligopygus  wetherbyi  is  most  closely  related  to  0.  floridanus  from  wliich  it 
can  be  distinguished  by  its  more  depressed  form,  more  petaloid  ambuhxcra,  broader  poriferous 
zones,  and  its  deeper,  longer  and  more  open  peristomial  depression.  It  also  resembles  0.  lialder- 
mani,  but  is  readily  separated  by  the  more  anterior  position  of  its  periproct. 

From  most  foreign  forms  0.  wetherhyi  can  be  readily  separated  by  its  more  profound 
depression  aroimd  the  peristome.  0.  costulatus  (Desor),  its  nearest  ally,  accordmg  to  De  Loriol, 
has  more  markedly  ridged  ambulacra,  a  more  swollen  and  shghtly  conical  test,  and  periproct 
nearer  the  peristome.  0.  oimin^serpentis  (Guppy),  from  supposedly  Eocene  deposits  of  Trini- 
dad, is  similar  but,  as  noted  by  Stefanmi,  difl^ers  in  having  a  less  profound  peristomial  cavity 
and  a  more  tumid  test. 

Localities. — Near  Gainesville,  Alachua  County  (De  Loriol) ;  6  imles  southwest  of  Gainesville, 
Santa  Fe  River,  Alachua  County;  and  Johnsons  Lime  Sink,  Levy  County,  Fla. 

Geologic  liorizon. — VicksbiU'g  group,  lower  Oligocene. 

Collection.— V .  S.  National  Museum  (137881a,  A;  137S81b,  B). 

Oligopygus  haldermaxi  (Conrad). 
Plate  LXXVIII,  figures  4a-cl,  5a-d. 

Discoidea  haldermani  Conrad,  1850,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  2,  p.  40,  PL  I,  fig.  12. 
Discoidea  haldermani  Coiirad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  75. 
Discoidea  haldermani  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  22. 
Discoidea  haldermani  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  88. 

Determinative  characters. — Test  with  tliick  walls,  marginal  outline  oval  to  subpentagonul 
and  slightly  undulating;  sides  tumid;  upper  surface  usually  elevated  anteriorly  and  depressed 


168  MESOZOIC   AND   CENOZOIC    ECHIXODEKMATA    OF    THE    UNITED    STATES. 

posteriorly,  sometimes  depressed  subconical;  under  surface  with  a  deep  and  more  or  less  long 
and  flaring  transverse  depression  around  the  iDeristome.  Ambulacral  areas  wide  at  the  ambitus, 
dorsal  portions  petaloid,  with  a  shght  constriction  at  the  ends  of  the  petals.  Apex  forward 
of  the  center.  Apical  system  central  or  subcentral.  Peristome  pentagonal,  opening  at  the 
bottom  of  the  depression  in  the  under  surface.     Periproct  very  small,  circular,  inframarginal. 

Dimensions. — Specimen  A:  Length  38  millimeters;  width  3.3  millimeters;  height  17  milli- 
meters.    Specimen  B:  Length  3S.5  millimeters;  width  31  miUimeters;  height  17  millimeters. 

Description. — It  is  thought  highly  probable  that  we  have  here  the  same  species  which  Conrad 
described  in  1850  under  the  name  of  Discoidea  Tialdermani,  as  some  of  the  specimens  studied 
came  from  near  the  same  place  that  Conrad's  form  did  and  correspond  fairly  well  with  his 
figures  and  description.  The  type  can  not  be  located;  and  as  Conrad  did  not  figure  the  under 
surface  of  his  form  there  is  some  doubt  regarding  the  position  of  the  periproct  and  the  presence 
of  a  pronounced  peristomial  depression.  The  fact  that  Conrad  assigned  liis  species  to  the  genus 
Discoidea,  points  to  an  inframarginal  position  for  the  periproct.  Should  Conrad's  type  ever  be 
found,  and  prove  to  be  different  from  the  present  species,  then  it  will  be  necessary  to  give  a  new 
name  to  this  OHgopygus. 

This  species  appears  to  be  the  most  abundant  and  also  the  most  variable  of  the  genus. 
The  writer  has  had  the  opportunity  of  studying  over  35  specimens,  including  both  young 
and  adult  forms,  varying  in  size  from  three-eighths  inch  to  1^  inches  in  length.  The  test  is 
unusually  thick.  The  marginal  outline  varies  from  regularly  oval  to  subpentagonal,  the  former 
being  more  usual  in  the  smaller  and  younger,  and  the  latter  in  the  larger  and  older  forms,  and  is 
slightly  undulating,  which  is  chiefly  due  to  broad  and  shallow  creases  in  the  middle  of  the  inter- 
ambulacral  areas.  The  margin  is  rounded  and  inflated,  the  anterior  end  usually  more  so  than 
the  posterior,  giving  that  end  a  bulging  appearance  in  a  forward  direction,  though  at  times  the 
two  ends  are  nearly  eciually  inflated.  The  upper  surface  is  somewhat  convex,  but  more  or  less 
depressed  and  flat  on  top,  sometimes  more  elevated  anteriorly  than  posteriorly,  sometimes 
depressed  subconical  in  form;  under  surface  tumid,  but  more  or  less  flattened,  and  with  a  deep 
transverse  depression  around  the  peristome.     The  apex  is  subcentral  or  excentric  anteriorly. 

The  ambulacral  areas  are  wide  at  the  ambitus,  from  which  they  gradually  narrow  to  the 
peristome  and  apex,  with  a  slight  constriction  at  the  ends  of  the  petaloid  portions;  the  anterior 
paired  ambulacra  cui-ving  posteriorly  on  approaching  the  peristomial  depression;  dorsal  por- 
tions varying  from  subpetaloid  to  slightly  petaloid,  the  odd  petal  being  slightly  longer  than  the 
others,  which  are  equal  or  nearly  equal  in  length.  Poriferous  zones  rather  broad,  gradually 
diverging  toward  their  extremities,  then  converging  shghtly  but  still  wide  apart  at  the  ends; 
outer  edges  slightly  depressed,  forming  ten  more  or  less  well  defined  linear  grooves  on  the  upper 
surface  of  the  test;  the  pores  equal  or  nearly  so,  small,  elliptical,  and  conjugate.  There  are  also 
several  pairs  of  very  small  pores  near  the  outer  end  of  each  plate  from  the  ends  of  the  petals 
to  beyond  the  ambitus.     The  interporiferous  areas  are  sUghtly  tumid. 

The  apical  system  is  central,  or  slightly  excentric  anteriorly.  The  madreporite  is  large, 
tumid  and  subcircular,  and  extends  to  and  between  the  posterior  radial  plates.  There  are 
four  genital  pores,  situated  at  the  edge  of  the  madreporite,  the  posterior  pair  being  farther  apart 
than  the  anterior;  and  there  are  five  small  radial  plates,  each  perforated  by  a  minute  pore. 

The  peristome  is  pentagonal  and  opens  at  the  bottom  of  a  rather  deep  transverse  depression  in 
the  middle  of  the  under  surface.  This  depression  varies  in  length  from  one-third  to  one-half  the 
width  of  the  test,  and  in  depth  from  one-fourth  to  one-third  the  height  of  the  test;  and  is  more 
or  less  open  and  flaring  in  form. 

The  periproct  is  very  small,  uniform,  circular,  and  inframarginal. 

Numerous  small,  uniform,  imperforate  tubercles,  surrounded  by  deep  scrobicules,  are  scat- 
tered irregularly  over  the  entire  surface  of  the  test. 

Belated  forms. — OHgopygus  Tialdermani  resembles  0.  wetTieriyi  and  0.  jloridanus  but  is 
readily  separated  from  both  by  the  inframargmal  position  of  its  pei'iproct.  Of  foreign  forms, 
0.  ovum-serpentis  (Guppy),  from  supposedly  Eocene  deposits  of  Trinidad,  is  closely  aUied  but 
has  its  periproct  farther  from  the  margin. 


OLIGOCENE   ECHINODEEMATA.  '  169 

Localities. — Richards  Quarry,  Ocala,  Marion  County,  and  Johnsons  Lime  Sink,  Levy 
County,  Fla.;  Flint  River  near  Bainbridge,  Baker  County,  Ga.  Conrad's  specimen  came  from 
a  well  near  Bainbridge,  Ga. 

Geologic  liorizon. — Vicksburg  group,  lower  Oligoceiie.  The  specimens  from  Ocala  are  from 
the  Ocala  limestone. 

Collections. — U.  S.  National  Museum  (112.506,  A;  164661,  B) ;  Wagner  Free  Institute  of 
Science. 

Oligopygus  floeidanus  Twitchell,  n.  sp. 

Plate  LXXIX,  figures  la-f. 

Determinative  cTiaracters. — Test  with  thick  walls,  oval,  narrowing  anteriorly;  sides  tumid; 
upper  surface  convex,  elevated  anteriorlj^,  slightly  depressed  posteriorly;  under  sm'face  with  a 
deep,  relatively  short  and  narrow  transverse  depression  around  the  peristome.  Ambulacral 
areas  wide  at  the  ambitus,  from  which  they  gradually  narrow  to  the  peristome  and  apex;  dorsal 
portions  subpetaloid;  petals  wide  open.  Apex  excentric  anteriorly;  apical  system  central  or 
slightly  excentric  anteriorly.  Peristome  pentagonal,  opening  at  the  bottom  of  the  depression 
in  the  under  surface.  Periproct  very  small,  circular,  situated  about  midway  between  the  peri- 
stome and  posterior  margin. 

Dimensions. — Length  37  millimeters;  width  31  millimeters;  height  19  millimeters.  The 
dimensions  of  another  specimen  were,  length  48  millimeters;  width  42  millimeters;  height  26 
millimeters. 

Description. — This  new  species  of  Oligopygus  is  rather  rare,  only  three  specimens  being 
known  to  the  writer.  De  Loriol  may  have  possessed  a  specimen,  for  some  of  the  characters  he 
ascribes  to  0.  wetJierhiji  apply  more  correctly  to  this  species.  The  test  is  usually  thick,  especially 
at  the  ends;  oval  on  marginal  outline,  though  somewhat  narrower  toward  the  anterior  end; 
margin  rounded  and  inflated,  the  anterior  end  more  so  than  the  posterior,  giving  that  end  a 
bulging  appearance  in  a  forward  direction.  The  upper  surface  is  convex,  somewhat  elevated 
forward  of  the  center,  declining  gradually  toward  the  posterior  end  and  sloping  somewhat 
steeply  on  the  sides;  under  surface  tumid  but  slightly  concave  transversely  near  the  middle, 
with  a  deep  transverse  depression  around  the  peristome.     The  apex  is  forward  of  the  center. 

The  ambulacral  areas  are  wide  at  the  ambitus,  from  which  they  gradually  narrow  to  the 
peristome  and  apex,  there  being  hardly  any  constriction  at  the  ends  of  the  petaloid  portions, 
the  anterior  paired  ambulacra  curving  posteriorly  on  approaching  the  peristomial  depression ; 
dorsal  portions  subpetaloid,  the  odd  petal  being  somewhat  longer  than  the  posterior  pair,  which 
are  somewhat  longer  than  the  anterior  pair.  The  poriferous  zones  are  narrow,  nearly  straight, 
and  gradually  diverge  from  their  origin  at  the  apex  to  their  extremities,  which  are  wide  apart; 
pores  small,  oval,  equal  and  conjugate.  There  are  also  several  pairs  of  very  small  pores  near 
the  outer  end  of  each  plate  from  the  ends  of  the  petals  to  beyond  the  ambitus  The  interporif- 
erous  areas  are  slightly  tumid,  standing  out  in  relief  in  the  unweathered  specimen,  so  as  to  form 
five  straight  radial  ridges  from  apex  to  ambitus. 

The  apical  system  is  central  or  somewhat  excentric  anteriorly.  The  madreporite  is  large 
and  tumid,  central,  shield  shaped ;  the  posterior  end  being  pointed  and  extending  between  the 
posterior  radial  plates.  There  are  four  genital  pores,  situated  at  the  edge  of  the  madreporite,  the 
posterior  pair  being  farther  apart  than  the  anterior;  and  there  are  five  small  radial  plates,  each 
perforated  by  a  very  small  pore. 

The  peristome  is  pentagonal  and  opens  at  the  bottom  of  a  deep,  transverse  depression  in 
the  middle  of  the  under  surface.  This  depression  is  relatively  short  and  narrow;  its  length  at  the 
siu'f  ace  being  about  one-third  tlie  width  and  its  depth  about  one-third  the  height  of  the  test.  Its 
anterior  wall  is  nearly  vertical  or  even  inclined  slightly  toward  the  anterior  end  but  at  a  much 
steeper  angle  than  the  posterior  wall,  thus  forming  a  deep,  narrow,  anteriorly  projecting 
concavity. 

The  periproct  is  very  small  and  circular;  and  situated  about  midway  between  the  peristome 
and  the  posterior  margin. 


170  MESOZOIC    AND   CEKOZOIC    ECHINODERMATA    OF    THE    UXITED    STATES. 

Numerous  small,  uniform,  imperforate  tubercles,  surrounded  by  deep  scrobicules,  are 
scattered  irregularly  over  the  entire  surface  of  the  test. 

Belated  forms. — OUgopngus  forldanus  is  closely  related  to  0.  wetlierhyi,  from  which  it  can  be 
separated  by  its  higher  and  less  flattened  upper  sm-face,  its  subpetaloid  ambulacra,  narrower 
poriferous  zones,  and  its  shorter,  less  flaring,  anteriorly  projecting  peristomial  depression.  It 
also  resembles  Oliqojiijgus  JtaJderwani  but  can  at  once  be  distuiguished  by  the  more  anterior 
position  of  its  periproct. 

Of  foreign  forms,  0.  ovum-serpentis  (Guppy),  from  supposedly  Eocene  deposits  of  Trinidad, 
is  closely  aUicd;  but  its  periproct  is  nearer  the  margin  and  its  peristomial  depression  less 
pronounced. 

Iiocality. — Nigger  Sink,  2  miles  south  of  Gainesville,  Alachua  County,  Fla. 

Geologic  horizon. — ^^^icksburg  group,  lower  Oligocene. 

Collection.— \] .  S.  National  Museum  (164660). 

Family  CASSIDULID.E. 

Genus  CASSIDTJLUS  Lamarck. 

Cassidtjlus   (Pygorhtnchtjs)  georgiensis  Twitchell,  n.  sp. 

Plate  LXXIX,  figures  2a-(l. 

Determinative  characters. — Test  broadly  oval,  upper  surface  convex,  moderately  elevated, 
sides  and  anterior  end  rounded;  posterior  end  obliquely  truncated,  under  surface  flat,  curving 
upward  slightly  posteriorly  to  meet  the  posterior  truncation  in  an  angular  margin;  apex  sub- 
central.  Ambulacral  areas  narrow;  petals  narrow,  nearly  closing,  the  posterior  pair  having  the 
nnier  poriferous  zone  of  each  petal  shorter  than  the  outer  zone.  Apical  system  excentric  ante- 
riorly. Peristome  excentric  anteriorly,  pentagonal,  transversely  elongate,  with  a  floscelle. 
Periproct  small,  subrhomboidal,  transverse;  located  at  the  top  of  the  rather  high  posterior  trun- 
cation, beneath  a  rounded,  somewhat  protruding  expansion  of  the  test. 

Dimensions. — -Length  26  millimeters;  width  22.5  millimeters;  height  15  millimeters.  An- 
other specimen,  of  nearer  average  size  gave,  length  .35  millimeters;  width  32  millimeters;  height 
20  millimeters. 

Description. — -Tliis  new  Cassidulus,  which  is  rather  rare,  only  throe  specimens  bemg  reported, 
has  a  test  which  is  broadly  oval  in  marginal  outline,  more  obtusely  rounded  posteriorly  than 
anteriorly,  and  obliquely  truncated  at  the  posterior  end.  The  upper  surface  is  regularly  convex, 
moderately  elevated,  in  the  form  of  a  low,  rounded  ridge  above  the  periproct,  sides  and  anterior 
end  rounded  and  inflated;  under  surface  flat,  curving  upward  slightly  posteriorly  to  meet  the 
oblique  posterior  trimcation  in  an  angular  margin,  the  angle  formed  being  about  75°.  The  apex 
is  subcentral. 

The  ambulacral  areas  are  narrow,  dorsal  portions  petaloid,  the  petals  narrow,  partly  open 
at  the  ends,  the  posterior  petals  longer  than  the  others,  which  are  nearly  equal  in  length.  The 
poriferous  zones  are  narrow;  the  inner  zone  of  each  of  the  posterior  pak  of  petals  shorter  than  the 
outer  zone;  outer  row  of  pores  slitlike,  inner  row  round;  pairs  of  pores  conjugate. 

Tlie  surface  of  the  test  is  closely  set  with  numerous  small  tubercles  which  increase  in  size 
on  the  under  surface  except  along  a  rather  wide  median  band  which  is  free  from  tubercles  and 
dotted  with  numerous  small  pits.  Tlie  tubercles  are  set  in  scrobicules  which  are  shallow  and 
irregularly  shaped  on  the  upper  surface;  but  become  larger,  deeper  and  more  regular  in  form  on 
the  under  surface. 

The  apical  system  is  excenti-ic  anteriorly.  The  only  details  which  can  be  made  out  are  the 
existence  of  four  genital  pores,  of  which  the  anterior  pair  are  nearer  together  than  the  posterior, 
and  five  small  perforated  radial  plates. 

Tire  peristome  is  excentric  anteriorly,  immediately  beneath  the  apical  system,  pentagonal, 
transversely  elongate,  mth  a  floscelle  of  which  the  phyllodes  are  rather  well  defined  and  the  bom- 
relets  are  large  and  prominent. 


OLIGOCENE   ECHINODEKMATA.  171 

Til  P.  poriproct  is  relatively  small,  about  3  or  4  millimeters  in  length,  subelliptical  to  sub- 
rhomboitlal,  transverse;  and  located  relatively  high  up  on  the  posterior  surface,  at  the  top  of  the 
rather  high  posterior  truncation,  beneath  a  rounded,  transverse,  somewhat  protruding  expansion 
■  of  the  test. 

Related  forms. — Ceissklulus  georgiensis  is  readily  separated  from  the  other  representatives  of 
the  genus  from  American  deposits.  In  some  features  it  resembles  Cassidulus  carolinensis,  but 
it  can  bo  distinguished  by  its  flatter  under  surface,  more  obtusely  rounded  and  more  angular  pos- 
terior margin,  higher  and  more  ol)liquo  posterior  truncation,  and  smaller  periproct.  Of  foreign 
forms  C.  georgiensis  resembles  some  forms  of  Pygorhi/iichus  grignonensis  (Defiance)  Agassiz  from 
the  Eocene  of  France,  but  can  be  separated  by  its  more  oblique  posterior  truncation,  more 
angular  posterior  margin,  and  higher  placed  periproct. 

Localities. — -Flmt  River,  near  Bainbridge,  Baker  Countj^,  and  2^  miles  north  of  Cuthbert, 
Ga. ;  Alabama  (exact  location  unknown). 

Geologic  horizon. — -Vicksburg  formation,  lower  Oligocene.  Possibly  also  Jackson  formation, 
upper  Eocene.     The  matrix  is  a  yellow  mass  of  foraminiferal  remains. 

Collections. — -U.  S.  National  Museum  (164347);  Yale  University. 

Cassidulus  (Pygorhynchus)  gouldii  (Bouve). 

Plate  LXXIX,  figures  3a-d;  Plate  LXXX,  figures  la-f,  2a-d. 

Pygorhynchus  gouldii  Bouvo,  1846,  Boston  Soc.  Nat.  History  Proc,  vol.  2,  p.  192. 

Pygorhynchus  gouldii  Bouv<5,  1847,  Am.  Jour.  Sci,  2cl  ser.,  vol.  3,  p.  437. 

Pygorhynchus  gouldii  Bouv^,  1847,  Annals  and  Mag.  Nat.  History,  1st  ser.,  vol.  20,  p.  142. 

Nucleolites  mortoni  Conrad,  1850,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  2d  ser.,  vol.  2,  p.  40,  PI.  I,  fig.  11. 

Pygorhynchus  gouldii  Bouve,  1851,  Boston  Soc.  Nat.  History  Proc,  vol.  4,*pp.  2-4,  two  figures  in  text. 

Pygorhynchus  gouldii  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  299. 

Ravenelia  gouldii  McCrady,  1859,  Elliott  Soc.  Nat.  History  Charleston  Proc,  vol.  1,  pp.  282,  283,  no  figure. 

Pygorhynchus  gouldii  Dujardin  and  Hupe,  1862,  Histoirenat.  zoophytes echinodermes,  p.  585. 

Pygorhynchus  gouldii  Conra.d,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  74. 

Pygorhynchus  gouldii  Conriid,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  22. 

Pygorhynchus  gouldii  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  91. 

Pygorhynchus  gouldii  Cotteau,  1888,  Paleontologie  I'ranfaise,  Echinides  eocenes,  vol.  1,  p.  550. 

Pygrohynchus  gouldii  Clark,  1891,  Johns  Hopkins  Univ.  Circ,  vol.  10,  No.  87,  p.  77. 

Nucleolitts  mortoni  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  200. 

Pygorhynchus  gouldii  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  696. 

Determinative  characters. — Test  irregularlj-  subconical,  broadly  ovate,  broadest  back  of 
middle;  variable  m  height;  margin  flat  along  the  sides,  angular  at  the  ends,  sharply  angular  under 
periproct;  upper  surface  elevated  anteriorly,  more  or  less  obliquely  flattened  and  depressed 
posteriorly,  under  surface  slightly  concave  longitudinally.  Apex  excentric  anteriorly.  Ambu- 
lacral  areas  broad  in  petaloidal  region,  narrow  beyond;  petals  long,  rather  sharply  pointed  at 
both  ends,  almost  closing.  Apical  system  excentric  anteriorly  or  subcentral.  Peristome  trans- 
vei'sely  elongate,  excentric  anteriorly,  more  so  than  the  apical  system,  M'ith  floscelle.  Periproct 
elliptical,  transverse,  supramarginal,  at  the  top  of  a  shallow  groove,  and  beneath  an  ovei hanging 
expansion  of  the  test. 

Dimensions. — Specimen  A  (type):  Length  .52  millimeters;  width  49  millimeters;  height  25 
millimeters.  Specimen  B:  Length  3.5  millimeters;  width  33  millimeters;  height  IS  millimeters. 
Specimen  C  (unusually  high):  Length  38  millimeters;  width  36  millimeters;  height  24  milli- 
meters. 

Description. — -The  species  was  reported  and  an  excellent  description  given  as  early  as  1S46 
by  T.  T.  Bouve  of  Boston,  whose  type  specimen  the  writer  has  had  the  privilege  of  studying. 
The  form,  which  though  one  of  the  best  known  in  the  literature  was  formerly  considered  rather 
rare,  has  been  shown  by  recent  collections  made  by  the  members  of  the  United  States  Geological 
Survey  and  others  to  be  one  of  the  most  abundant  of  American  Cenozoic  echinoids.  It  is 
especially  abundant  in  Florida,  where  it  has  been  found  at  many  localities.  The  species  is  very 
variable,  its  extreme  specimens  differing  so  much  in  a  number  of  details  that  they  might  be 


172  MESOZOIC   A]S^D   CEK'OZOIC    ECHIXODEKMATA    OF    THE    UNITED    STATES. 

regarded  as  different  species  were  it  not  for  the  intermediate  forms  found  in  the  large  amount 
of  available  material.     Many  of  the  specimens  are  only  well-preserved  casts. 

The  test  is  irregularly  subconical  in  form;  the  marginal  outline  broadly  ovate,  broadest 
back  of  the  middle ;  margm  thick  and  vertically  flattened  along  the  anteriorly  converging  side 
portions,  more  or  less  angular  at  the  ends,  sharply  angular  beneath  the  pcriproct.  The  upper 
sm-face  varies  from  rather  low  and  depressed  to  moderately  high.  It  is  irregularly  subconical ; 
the  apex  being  more  or  less  excentric  anteriorly,  the  side  and  anterior  surfaces  sloping  nearly 
equally  and  somewhat  steeply  though  with  a  more  or  less  rounded  contour,  and  the  posterior 
surface  sloping  less  steeply  and  being  more  or  less  flattened,  except  for  a  slight  tumidity  above 
the  periproct.  The  under  sm-face  is  concave  along  the  longitudinal  median  area.  The  apex  is 
excentric  anteriorly,  sometimes  coincident  with,  sometimes  anterior  to  the  apical  system. 

The  ambulacral  areas  are  narrow  at  the  ambitus,  dorsal  portions  petaloid;  petals  rather 
wide,  long,  the  posterior  pan-  slightly  longer  than  the  anterior  pair  which  are  slightly  longer  than 
the  odd  petal,  rather  sharply  pointed  at  both  ends,  almost  closing  at  their  extremities.  The 
poriferous  zones  are  rather  wide,  slightly  depressed;  pores  subequal,  outer  row  oval,  imier  row 
round;  pairs  of  pores  conjugate;  interporiferous  areas  slightly  tumid. 

The  surface  of  the  test  is  closely  set  with  small  scrobiculate  tubercles  which  mcrease  in  size 
on  the  under  surface  except  along  a  rather  narrow  pitted  median  area. 

The  apical  system  is  excentric  anteriorly  in  most  specimens,  but  is  subcentral  m  some.  In 
most  it  is  coincident  -with  the  apex  but  in  some  it  is  slightly  back  of  it.  Because  of  the  poor 
character  of  the  specimens,  the  details  can  rarely  be  made  out.  There  are  four  perforated  basal 
plates,  the  anterior  genital  pores  being  nearer  together  than  the  posterior,  and  five  small  perfo- 
rated radial  plates. 

The  peristome  is  pentagonal,  somewhat  elongate  transversely,  excentric  anteriorly,  more  so 
than  the  apical  system,  bemg  about  three-eighths  the  length  of  the  test  from  the  anterior  margin; 
and  apparently  more  fixed  in  its  relative  position  than  the  apical  system.  It  is  surrounded  bj^  a 
well-defined  floscelle  with  rather  prominent  bourrelets.  On  the  casts  the  phyllodes  form  prom- 
inent radial  ridges  around  the  peristome. 

The  periproct  is  moderately  large,  elliptical,  transverse,  supramarginal,  rather  low  and  near 
the  posterior  end,  beneath  a  low,  romided,  transverse  expansion  of  the  test.  Beneath  the  peri- 
proct there  is  a  depression  which  renders  the  margin  at  this  point  thiimer  or  more  sharply  angular 
than  it  is  elsewhere. 

Related  forms. — Among  American  forms  Cassidulus  gouldii  is  most  nearly  related  to  C.  ala- 
hamensis  but  can  readily  be  distinguished  by  its  smaller  size,  less  subquadrate  form,  and  more 
steeply  sloping  sides.     It  does  not  appear  to  very  closely  resemble  any  foreign  forms. 

Localities. — -Baker  County  (type);  Laurenden  Creek;  Hawkuisville ;  A.  E.  Belcher's  well, 
Decatm- County;  32  miles  south  of  Macon,  on  Georgia  &  Florida  Railroad;  EUaville;  2i  miles 
north  of  Cuthbert,  Ga.  Two  miles  south  of  Gainesville;  6  miles  southwest  of  Lake  City;  Santa 
Fe  River,  Alachua  County,  Pembertons  Ferry,  Withlacoochee  River  4  and  5  miles  west  of  Live 
Oak;  deep  wells  at  Padlock,  7  miles  south  of  Live  Oak;  Sulphur  Sprmgs  Ferry,  Suwannee 
County,  Fla. 

Geologic  horizon.— Vicksburg  group,  lower  Oligocene,  possibly  Eocene  also.  Bouve  said 
his  form  was  from  the  "Millstone  grit"  and  Conrad  said  his  was  from  the  "Buhrstone";  con- 
sequently the  species  has  hitherto  been  regarded  as  Eocene;  but  nearly  all  of  the  large  nmnber  of 
specimens  studied  by  the  writer  came  from  Oligocene  deposits. 

Collections.— Boston  Society  of  Natural  History  (17.56,  A);  U.  S.  National  Museum  (1.37904, 
B;  137904a,  C);  Academy  of  Natural  Sciences  of  Philadelphia;  Wagner  Free  Institute  of 
Science. 

Cassidulus  (Pygorhynchus)  alabamensis  Twitchell,  n.  sp. 

Plate  LXXX,  figures  3a-cl. 

Determinative  characters.— Test  large,  subquadrate,  depressed;  upper  surface  convex, 
declining  from  apex  nearly  equally  on  all  sides;  mider  surface  concave  longitudinally.  Apex 
subcentral,  slightly  to  the  rear  of  the  anteriorly  eccentric  apical  system.     Ambulacral  areas 


OLIGOCENE   ECHINODEKMATA.  173 

broad  in  petaloidal  portion,  narrow  beyond;  petals  long,  subcqual  in  length,  almost  closing. 
Peristome  rather  large,  pentagonal,  transversely  elongate,  exccntric  anteriorly,  more  so  than  the 
apical  system,  with  a  floscelle.  Periproct  rather  large,  elliptical,  transverse,  supramarginal,  at 
the  top  of  a  broad  shallow  groove  and  beneath  an  overhanging  expansion  of  the  test. 

Dimensions. — Length  69  millimeters;  width  63  millimeters;  height  29  millimeters. 

Description. — This  large  Cassidulus,  the  largest  representative  of  the  genus  from  American 
Cenozoic  deposits,  is  very  rare,  only  a  few  specimens  having  been  discovered.  The  test  is 
moderate  to  large  in  size,  momidlike  in  form,  depressed,  subquadrate  in  marginal  outlme;  margin 
thick,  somewhat  flattened  on  the  sides,  more  angular  at  the  ends,  sharply  angular  beneath  the 
periproct.  The  upper  surface  is  convex,  and  declines  gently  from  the  apex  nearly  equally  on 
all  sides,  though  the  side  outlines  tend  to  be  straight  while  the  end  outlines  tend  to  be  curving; 
a  slight  tumidity  exists  along  the  medial  line  above  the  periproct.  The  under  surface  is  decidedly 
concave  along  a  broad,  longitudinal  median  area.  The  apex  is  nearly  central,  being  but  slightly 
excentric  anteriorly. 

The  ambulacral  areas  are  narrow  at  the  ambitus,  dorsal  portions  petaloid;  petals  rather 
wide,  long,  of  nearly  equal  length,  almost  closing  at  their  extremities.  The  poriferous  zones  are 
rather  wide,  slightly  depressed ;  pores  subequal,  outer  row  oval,  imier  row  round ;  pairs  of  pores 
conjugate;  interporiforous  areas  slightly  tumid. 

The  surface  of  the  test  is  closely  sot  with  small  scrobiculate  tubercles  which  increase  in  size 
on  the  under  surface  except  along  a  rather  narrow  median  pitted  area. 

The  apical  system  is  large  and  slightly  excentric  anteriorly,  somewhat  anterior  to  the  apex. 
There  are  four  genital  pores,  the  anterior  pair  being  nearer  together  than  the  posterior,  and  there 
are  five  minute  pores  perforating  the  radial  plates. 

The  peristome  is  rather  large,  pentagonal,  transversely  elongate,  excentric  anteriorly,  more 
so  than  the  apical  system,  being  about  three-eighths  the  length  of  the  test  from  the  anterior 
margin.     It  is  surrounded  by  a  large,  well-defined  floscelle,  with  prominent  bourrelets. 

The  periproct  is  rather  large,  elliptical,  transverse,  supramarginal,  rather  high  up,  at  the 
top  of  a  broad  shallow  groove  and  beneath  a  rounded  overhanging  expansion  of  the  test. 

Related  forms. — Cassidulus  alahamensis  is  closely  related  to  C.  gouldii,  from  which  it  is  readily 
separated  by  its  greater  size  and  its  relatively  low  almost  regularly  convex  upper  surface.  It 
does  not  appear  to  be  closely  related  to  any  foreign  form. 

Localities. — Natural  Bridge,  St.  Stephens,  Ala.;  A.  E.  Belcher's  well,  Decatur  County,  Ga. 

Geologic  horizon. — St.  Stephens  limestone  (upper  part),  lower  Oligocene. 

Collection. — -Johns  Hopkins  University  (type). 

Genus  EdnNOLAMPAS  Gray. 

EcHiNOLAMPAS  ALDRicHi  Twitchell,  n.  sp. 

Plate  LXXXI,  figures  la-d,2. 

Determinative  characters. — ^Test  large,  subcuxular;  margin  rounded;  upper  surface  depressed 
subcorneal,  sloping  more  steeply  anteriorly  than  posteriorly;  under  surface  concave,  posterior 
end  slightly  rostrate;  apex  forward  of  the  center.  Ambulacral  areas  rather  narrow,  dorsal  por- 
tions petaloid;  petals  long,  open  at  the  ends,  poriferous  zones  of  some  petals  unequal  in  length, 
interporiferous  areas  tumid.  Apical  system  excentric  anteriorly.  Peristome  large,  excentric 
anteriorly,  slightly  less  so  than  apical  system,  pentagonal,  transversely  elongate,  surroundeil  by  a 
floscelle  with  feeble  phyllodes  and  bourrelets.  Periproct  large,  elliptical,  transverse,  infra- 
marginal. 

Dimensions. — Specimen  A  (type,  smaller  than  the  average):  Length  56  millimeters;  width 
54  millimeters;  height  26  millimeters.  Largest  specimen:  Length  SO  millimeters;  width  75 
millimeters;  height  37  millimeters. 

Description. — Of  this  fine  Echuiolampas  the  only  specimens  so  far  reported  belong  to  T.  H. 
Alth'ich,  of  Birmingham,  Ala.,  in  whose  honor  the  species  is  named.*     The  test  is  large  (ranging 

1  The  Aldrich  collection  is  now  owned  by  the  Johns  Hopkins  University. 
39800°— 15 12 


174  MESOZOIC    AND    CENOZOIC    ECHIKODEEMATA    OF    THE    UNITED    STATES. 

from  2  to  3  inches  in  diameter)  and  about  half  as  liigh  as  broad.  The  marginal  outline  is  broadly 
oval  to  subcircular;  sometimes,  especially  in  the  larger  and  older  forms,  slightly  broader  pos- 
teriorly than  anteriorly  and  broadly  V-shaped  at  the  posterior  end;  margin  tumid  and  rounded. 
The  upper  surface  is  dt?pressed  subconical,  though  at  times  approaching  a  depressed  subhemi- 
spherical  contour,  sloping  more  steepty  anteriorly  and  on  the  sides  than  posteriorly;  under  sur- 
face concave,  though  slightly  tumid  around  the  margin  except  along  the  posterior  ambulacral 
areas  where  there  are  broad  and  very  shallow  depressions  which  give  the  posterior  end  of  the 
test  a  slightly  rostrate  appearance.  The  apex  is  forward  of  the  center,  about  two-fifths  of  the 
length  of  the  test  from  the  anterior  end,  coincident  with  the  apical  system. 

The  ambulacral  areas  are  rather  narrow,  dorsal  portions  petaloid;  petals  long,  rather  narrow, 
open  at  their  extremities,  the  posterior  pair  slightly  longer  than  the  anterior  pair  which  are 
slightly  longer  than  the  odd  petal;  interporiferous  areas  tumid.  The  poriferous  zones  are 
rather  narrow,  slightly  depressed,  the  inner  zone  of  each  of  the  posterior  petals  and  the  anterior 
zone  of  each  of  the  anterior  paired  petals  being  slightly  straighter  and  shorter  than  its  fellow, 
the  differences  being  the  more  pronounced  in  the  anterior  pair;  outer  pores  slitlike,  inner  pores 
round,  pairs  of  pores  conjugate. 

The  whole  surface  of  the  test  is  closely  set  with  very  small,  uniform  tubercles  in  sunken 
scrobicules. 

The  apical  system  is  excentric  anteriorlj'.  There  are  four  perforated  basal  plates,  the 
anterior  pair  of  genital  pores  being  nearer  together  than  the  posterior,  and  five  small  perforated 
radial  plates.  The  madreporite  is  large,  occupying  the  larger  part  of  the  system,  and  extending 
back  between  the  posterior  radial  plates. 

The  peristome  is  rather  large,  excentric  anteriorly,  slightly  less  so  than  the  apical  system, 
pentagonal,  transversely  elongate,  at  the  deepest  portion  of  the  concave  under  surface,  and 
surrounded  by  a  floscelle  with  feeble,  straight  phj'llodes  and  low,  broad,  tumid  bourrelets. 

The  periproct  is  rather  large,  elliptical,  the  posterior  side  slightly  less  convex  than  the 
anterior,  transverse,  inframarginal,  very  close  to  the  posterior  margin. 

Related  forms. — EcMnolampas  aldrichi  is  quite  unlike  EcTiinoJampas  appendiculatus,  the 
onty  other  representative  of  the  genus  found  in  the  Cenozoic  deposits  of  the  United  States.  Of 
foreign  forms  it  is  very  similar  to  EcMnolampas  affinis  (Goldfuss)  Agassiz,  which  occurs  in  the 
Eocene  of  Belgium  and  France,  but  it  is  to  be  distinguished  bj'  its  more  anteriorly  excentric 
apex  and  the  somewhat  unequally  excentric  positions  of  its  apical  system  and  peristome.  It 
also  resembles  EcMnolampas  insignis  Duncan  and  Sladen  from  the  Nummulitic  series  of  the 
Tertiary  of  India,  from  which,  however,  it  differs  in  being  smaller,  less  elevated,  and  having  its 
apex  more  excenti'ic  anteriorly. 

Localities. — Gainestown,  and  Choctaw  Bluff,  Alabama  River,  Alabama;  Mississippi  (exact 
locality  unknown). 

Geologic  horizon. — St.  Stephens  limestone,  Alabama;  Vicksburg  limestone,  Mississippi; 
lower  Oligocene. 

Collection. — Johns  Hopkins  University  (T  1099,  A). 

Suborder  STERNATA. 

Family  SPATANGIDiE. 
Genus  AGASSIZIA  Valentin. 

Agassizia  coneadi  (Bouve). 

Plate  LXXXI,  figures  3a-fl. 

Eemiaster  conradi  Bouvi?,  1851,  Boston  Soc.  Nat.  Hist.  Proc,  vol.  4,  p.  3,  figures  in  text. 

Bemiaster  conradi  Desor,  1858,  Sjiiopsis  cchiiiodermes  fossiles,  p.  373. 

Eemiaster  conradi  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  75. 

Eemiaster  conradi  Conrad,  1866,  Check  list,  Eocene  and  Oligocene. 

Ditremaster  conradi  Cotteau,  1887,  Paleontologie  franfaise,  Echinides  eocenes,  vol.  1,  p.  427. 

Agassizia  floridana  De  Loriol,  1887,  Recueil  zool.  Suisse,  vol.  4,  pp.  398— iOl,  PI.  XVII,  fig.  9. 

Opissaster  conradi  Stefanini,  1911,  Soc..  geol.  italiana  Boll.,  vol.  30,  p.  700. 

Agassizia  floridana  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  rol.  30,  p.  705. 


OLIGOCENE    ECHIXODERMATA.  175 

Determinative  characters. — Test  small,  ovoid,  iippei"  surface  high.  Apical  system  very 
excentric  posteriorly.  Ambulacra  narrow,  anterior  indistinct  in  shallow  depression  and  with 
short  petals  in  shallow  groove.  Surface  covered  with  very  small  tubercles.  Peripetalous 
fasciole  indistinct.     Peristome  large.     Periproct  high  on  posterior  truncation. 

D'unensions. — Length  18  millimeters;  width  16  millimeters;  height  14  millimeters. 

Description. — This  small  delicate  form  is  different  from  any  other  Tertiary  species.  The 
test  is  ovoid,  much  elevated,  the  high  apex  giving  a  subcorneal  appearance  to  the  upper  surface. 
The  apex  is  very  excentric  posteriorly  and  the  upper  surface  slopes  from  it  in  all  du'ections. 
The  under  surface  is  convex  except  for  the  peristomial  depression. 

The  ambulacra  are  narrow,  the  anterior  hardly  distinguishable  on  a  nearly  flush  surface 
which  shows  a  slight  depression.  The  paired  ambulacra  have  short  petals  in  shallow  grooves, 
the  posterolateral  pair  being  not  half  the  length  of  the  anterolateral. 

The  interambulacra  are  broad,  the  upper  portions  of  the  paired  areas  near  the  apex  being 
gibbous  and  terminating  in  short,  narrow  ridges.  The  posterior  interambulacruni  has  a  pro- 
nounced truncation,  which  slopes  inward  so  that  the  periproct  is  not  visible  from  above  but  is 
from  below. 

The  fascioles  are  very  narrow  and  only  traces  of  them  can  be  seen  here  and  there. 

The  peristome  is  large  and  bilabial.  The  periproct  is  quite  large,  transverse  oval,  slightly 
overhung  by  the  projecting  interambulacrum. 

The  apical  system  consists  of  four  genital  plates,  the  perforations  of  which  are  near  together. 

Related  forms. — This  species  is  easily  distinguished  from  other  species  of  this  genus  by  its 
much  elevated  upper  surface,  slightly  conical  at  the  apex,  and  its  very  excentric  apex  posteriorly. 
The  sharp  truncation  of  the  posterior  surface  is  very  characteristic.  These  and  other  characters 
distinguish  it  from  A.  excentrica,  which  still  lives  in  the  Caribbean  Sea  and  near  the  coasts  of 
Florida  and  also  from  A.  clevei  of  the  iliocene  of  the  island  of  St.  Barthelemy. 

Localities. — Georgia  (Bouve) ;  near  Bainbridge  (figured  specimen)  and  3^  miles  south  of 
Sasser  on  Dawson-Albany  public  road,  Georgia;  near  Gainesville,  Fla. 

Geologic  horizon. — Lower  Oligocene. 

Collection.  —\J.  S.  National  iluseum  (164744) ;  Geological  Survey  of  Georgia. 

Genus  SCHIZASTEB  Agassiz. 
ScHiZASTER  FLOEIDANUS  Clark,  n.  sp. 

Plate  LXXXII,  figures  la-c. 

Determinative  characters. — Test  rather  large,  cordiform,  high  posterior  upper  surface,  nearly 
flat  lower  surface.  Ambulacra  in  broad,  deep  grooves,  the  petals  of  the  paired  ambulacra  being 
very  pronounced.  Posterior  truncation  prominent  with  high  perinroct.  Peristome  near  anterior 
margin. 

Dimensions. ^Length  50  millimeters;  width  24.5  millimeters;  height  .30  millimeters. 

Description. — The  species  is  represented  only  by  forms  in  which  the  test  has  been  replaced 
by  silica,  obliterating  some  of  the  features  but  admirably  preserving  others. 

The  test  is  of  rather  large  size,  cordiform,  with  a  sloping  upper  surface  which  extends  up 
from  the  depressed  anterior  margin  to  the  much  elevated  posterior  margin.  The  lower  surface 
is  nearly  flat. 

The  ambulacra  are  broad,  the  anterior  ambulacrum  being  in  a  broad  deep  groove  which 
passes  over  the  anterior  margin.  The  paired  ambulacra  have  broad  deep  petals,  the  antero- 
lateral pair  being  about  one  and  one-half  times  as  long  as  the  posterolateral. 

The  interambulacra  are  wide  and  are  sUghtly  gibbous  near  the  apex.  The  posterior  area 
has  a  sharp  ridge  reaching  to  the  posterior  margin.  A  pronounced  truncation  characterizes  this 
area,  the  slope  being  actually  inward  and  the  periproct  being  found  high  on  the  surface.  The 
peristome  is  large  and  near  the  anterior  margin. 

Locality. — Johnsons  Sink,  Levy  County,  Fla. 

Geologic  horizon. — Vicksburg  group,  lower  Oligocena 

Collection. — U.  S.  National  Museum  (164655). 


176  '   MESOZOIC   AND   CEKOZOIC    ECHINODEEMATA   OF    THE    UNITED    STATES. 

SCHIZASTER    AMERICANA    Clark,  11.  Sp. 
Plate  LXXXII,  figures  2a-d. 

Determinative  characters. — Test  medium  size,  subpeiitagonal,  as  wide  as  long,  upper  surface 
elevated  posteriorly.  Ambulacra  narrow,  the  anterior  deeply  sunken  in  deep  groove;  the  paired 
ambulacra  with  short  petals,  the  posterior  about  one-half  the  length  of  the  anterior.  Interam- 
bulacra  broad,  prominent.  Peristome  near  anterior  margin,  in  weU-marked  depression.  Peri- 
proct  high  on  truncated  posterior  margin,  peripetalous  and  lateral  fascioles  clearly  marked. 

Dimensions. — ^Length  39  millimeters;  width  39  millimeters;  height  25  millimeters. 

Description. — The  species  has  a  test  of  medium  size,  rather  taU,  subpentagonal,  as  wide  as 
lono-,  sloping  up  from  the  anterior  margin  to  the  nearly  central  apical  system,  beyond  which  a 
sharp  rise  continues  toward  the  posterior  margin,  its  highest  point  being  about  midway. 

The  ambulacra  are  narrow,  the  anterior  one  situated  in  a  deep,  moderately  wide  groove  that 
indents  the  anterior  margin.  The  paired  ambulacra  have  deep  short  petals,  the  anterolateral 
being  about  twice  as  long  as  the  posterolateral. 

The  interambulacra  are  broad  and  somewhat  gibbous  on  the  sides.  The  posterior  inter- 
ambulacrum  is  much  elevated  and  rather  narrow.  The  surface  is  covered  with  numerous  small 
but  clearly  distinct  tubercles  with  small  granules  between  them.  The  peripetalous  and  lateral 
fasciole  can  be  readily  traced. 

The  apical  system  is  small  and  nearly  central  in  position.  The  peristome  is  near  the  anterior 
margin  m  a  well-marked  depression.     The  periproct  is  high  on  the  truncated  posterior  margin. 

Localities. — Yost  limekiln  near  Brandon  station,  Rankin  County  (type),  and  Clarke  County, 
Miss. ;  5  mUes  south  of  EllaviUe,  on  EllaviUe-Americus  pubhc  road,  Georgia. 

Geologic  horizon. — Vicksburg  formation,  lower  Ohgocene. 

Collection. — U.  S.  National  Museum  (165695) ;  Geological  Survey  of  Georgia. 

Etjpatagus  floridanus  Clark,  n.  sp. 
Plate  LXXXII,  figures  3a-cl;  Plate  LXXXIII,  figures  la-c,  2a-<l. 

Determinative  characters. — Testlarge,  elongate,  subcordiform,  depressed,  sloping  from  anterior 
margin  to  point  half  way  from  apical  system  to  posterior  truncation.  Ambulacra  nearly  flush, 
poriferous  zones  somewhat  sunken,  paired  ambulacra  with  long  petals.  Interambulacra  with 
large  perforate  and  crenulate  tubercles  irregularly  scattered  over  surface.  Fascioles  distinct. 
Peristome  small.     Periproct  large. 

Dimensions. — Specimen  A:  Length  65  millimeters;  width  56.5  millimeters;  height  31.5 
miUimeters.  Specimen  B:  Length  67  millimeters;  width  56  millimeters;  height  30  millimeters. 
Specimen  C:  Length  49  millimeters;  width  39.5  milUmetei-s;  height  23  mUUmeters. 

Description. — A  number  of  specimens  of  this  striking  form  have  been  found  in  the  Oligocene 
of  Florida.  The  test  is  large,  elongate,  subcordiform,  and  depressed.  The  upper  surface  slopes 
from  the  low  anterior  margin  gradually  to  the  high  posterior  apex  which  is  situated  about  half- 
way from  the  apical  system  to  the  beginning  of  the  posterior  truncation.  The  lower  surface  is 
nearly  flat. 

The  ambulacra  are  wide  nearly  flush  and  the  poriferous  zones  somewhat  sunken.  The  paired 
ambulacra  have  long,  closed  petals  the  posterolateral  longer  than  the  anterolateral.  The  pore 
openings  of  the  petaloidal  portions  are  small  and  round,  the  pore  pairs  connected  by  deep  furrows. 

The  interambulacra  consist  of  large  plates  covered  somewhat  irregularly  with  large  per- 
forate and  crenulate  tubercles,  the  greater  number  occurrmg  in  more  or  less  horizontal  rows  along 
the  upper  part  of  the  plates  above  the  ambitus. 

The  apical  system  is  anterior  to  the  center  of  the  upper  surface,  is  small  and  nearly  flush. 

The  fascioles  are  distinct  here  and  there.  The  peristome  is  small  and  semicircular.  The 
periproct  is  large,  occupying  much  of  the  truncated  surface. 

Related  forms. — Tliis  species  has  many  points  of  similarity  to  E.  clevei  Cotteau  of  St.  Bar- 
thelemy  Island,  although  it  dift'ers  in  some  minor  particulars.  It  may  prove  to  be  the  same 
species. 


OLIGOCENE    ECHINODEKMATA.  177 

Locality. — Johnsons  Sink  (type  specimen  A),  Levy  County  (type  specimens  B  and  C),  Fla. 
Geologic  Ttorizon. — Vicksburg  group,  lower  Oligocene. 

Collections. — U.  S.  National  Museum  (137881,  A);  "Wagner  Free  Institute  of  Science  (B.); 
Museum  of  Comparative  Zoology. 

Class  HOLOTHITETOTDEA. 

Order  PARACTINOPODA. 

Family  SYNAPTID.f;. 

Genus  CHIRODOTA  Eschscholtz. 

Chirodota  sp. 

Chirodota  sp.  Cunningham,  1895,  Am.  Micr.  Jour.,  vol.  16,  pp.  193-196,  and  figs.  1  and  2. 

Description. — -Small  holothurian  plates  are  figured  by  Cunningham  and  referred  to  the  genus 
Chirodota.     No  material  has  been  accessible  for  the  present  investigation. 

Locality. — -Near  Red  Bluff  station,  Chickasawhay  River,  Clarke  County,  Miss. 
Geologic  horizon. — Vicksburg  limestone,  lower  Oligocene. 
Collection. — -K.  M.  Cunningham,  Mobile,  Ala. 

Genus  SYNAPTA  Eschscholtz. 

Synapta  sp. 

Synapta  sp.  Cunningham,  1S95,  Am.  Micr.  Jour.,  vol.  16,  pp.  193-196,  and  figs.  3-6. 

Description.- — Fragments  of  small  plates  and  a  spicule   are  figured  by  Cunningham    and 
referred  to  the  genus  Sjoiapta.     No  material  has  been  accessible  for  the  present  investigation. 
Locality. — Near  Red  Bluff  station,  Cliickasawhay  River,  Clarke  County,  Miss. 
Geologic  horizon. — Vicksburg  limestone,  lower  Oligocene. 
Collection. — -K.  M.  Cunningham,  Mobile,  Ala. 


MIOCENE   ECHINODERMATA. 

Class  STELLEKOIDEA. 

Subclass  ASTEROIDEA. 

Order  CRYPTOZONIA. 

Family  ASTERIID.E. 

Genus  ASTERIAS  liinne. 

ASTERIAS    EEMONDII    Gabb. 

Ast-eriasremondiiGahh,  1869,  Geol.  Survey  California,  Paleontology,  vol.  2,  pp.  37,  38,  PI.  XIII,  fig.  69. 
Asterias  remondi  Cooper,  ISSS.  State  ilineralogist  California  Seventh  Ann.  Kept.,  p.  270. 
Asterias  nmondi  Weaver,  1909,  Univ.  California  Dept.  Geology  Pub.,  vol.  5,  No.  16,  p.  261. 

Description. — -Since,  no  material  representing  this  species  has  been  accessible  for  study  the 
description  of  Gabb  is  given  verbatim: 

Animal  large,  robust,  five  rayed;  rays  more  than  twice  as  long  as  the  diameter  of  the  disk,  thick  on  the  margin. 
Upper  surface  covered  by  short,  club-shaped  spines,  narrow  toward  the  base,  and  bluntly  rounded  above;  on  the  sides 
these  same  spines  are  more  closely  placed,  and  on  the  undersurface  they  are  so  close  that  they  are  in  contact;  ambu- 
lacroe  broad,  bearing  numerous  small,  A"ery  slender  spines. 

Localitxj. — Star  Fish  Point,  Martinez,  Contra  Costa  Cotmty,  Cal.  (Cooper),  Sau  Pablo  Bay, 
Cal.  (Weaver). 

Geologic  Jionzon. — ^Sau  Pablo  formation,  upper  Miocene. 
Collection. — Unknown. 

Subclass  OPHIUROIDEA. 

Order  ZYGOPHIUR^. 

Family  OPHIODERMATID.F. 

Genus  OPHIODERMA  Muller  and  Trosch. 

Ophioderma  (?)  sp. 

Plate  LXXXIV,  figure  1. 

Ophioderma  ?  sp.  Clark,  1904,  Maryland  Geol.  Survey,  Miocene,  p.  433,  PI.  CXX,  fig.  3. 

Description. — ^Fragments  of  the  arms  of  an  Ophiurian  occur  in  the  indurated  ledge  just  above 
sea  level  along  St.  Marys  River.  It  is  impossible  to  determine  the  relations  of  the  form  with 
accuracy,  but  it  is  probably  an  Ophioderma.  The  fragments  were  found  in  the  interior  of  the 
shells  of  large  gastropods. 

Locality. — St.  Marys  River,  Md. 

Geologic  Jionzon. — St.  Marys  formation,  middle  Miocene. 

Collection. — Johns  Hopkins  University  (T  1000). 

Family  AMPHIURID^. 

Genus  AMPHIURA  Fcirbes. 
Amphiura  sANCTiBCRUCis  Ai-nold. 
Plate  LXXXIV,  figures  2  and  3. 
Amphiura  sanctiecmcis  Arnold,  1903,  U.  S.  Nat.  Mus.  Proc,  vol.  34,  pp.  403-406,  PI.  XI,  figs.  1,  2. 
Description.^X.vi\o\A  describes  the  species  as  follows: 

Disk  attaining  a  diameter  of  13  millimeters,  delicate,  covered  with  small  naked  overlapping  scales.     Arms  five, 
long,  slender,  even  or  tapering  very  slightly  and  more  or  less  flattened.     Ann  spines  moderately  short  and  sharp 
178 


MIOCENE   ECHINODEKMATA.  179 

pointed,  approximately  equal  in  length  to  the  width  of  the  doi-sal  median  plates.     Under  arm  plates  simple,  breadth 
about  IJ  length;  lower  arm  plates  deeply  grooved  in  the  median  line. 

Disk  pentagonal  in  outline,  the  arms  pas.sing  out  from  the  sides  rather  than  from  the  angles,  this  being  due  to  the 
spreading  of  the  disk  upon  compression  by  the  containing  fine  clayey  sediments;  whole  dorsal  surface  of  disk  covered 
with  overlapping  scales,  which,  in  the  cast  serving  as  the  type,  are  minutely  shallowly  punctuate  corresponding  to 
numerous  microscopic  protuberances  in  the  original  animal.  Radial  shields  moderately  large,  of  a  short,  pear-seed 
shape,  pointed  within,  outer  edge  sharply  rounded,  inner  edges  nearly  straight  and  separated  by  five  prominently 
overlapping  scales  (the  continuation  of  the  upper  arm  scales,  but  shorter  than  the  latter)  which  narrow  rapidly  toward 
the  points  of  the  shields.  Between  the  radial  shields  of  adjacent  arms  are  about  seven  rows  of  small  overlapping 
plates,  the  middle  row  apparently  much  larger  than  the  othere.  The  specimen  exhibiting  the  ventral  side  is 
BO  much  crushed  that  its  characteristics  are  unrecognizable.  Upper  arm  plates  simple,  small,  breadth  about  IJ 
length,  slightly  narrowed  within,  broader  without,  straight  front,  back,  and  sides.  Side  plates  small,  triangular, 
with  sharp  cornered,  beveled  edges.  Under  arm  plates  quite  similar  to  upper,  except  deeply  medially  longitudinally 
grooved.     Spines  at  least  four  to  a  segment;  about  IJ  times  length  of  upper  arm  plates,  rounded,  sharp. 

Dimensions. — Specimen  exhibiting  dorsal  surface:  Diameter  of  disk  13  millimeters;  arms  at  least  25  millimeters 
long  and  probably  several  times  this  amount;  width  near  disk  2  millimeters,  upper  arm  plates  0.7  to  0.8  millimeter 
long. 

Specimen  exhibiting  ventral  surface:  Diameter  of  disk  6.5  millimeters;  arm  at  least  20  millimeters  long  and 
probably  at  least  twice  this  length  judging  by  taper. 

Notes. — The  two  specimens  upon  which  this  species  is  founded  are  beautifully  preserved  molds,  the  larger  one, 
which  is  taken  as  the  type,  showing  the  dorsal  surface,  the  smaller  one  the  ventral.  As  would  be  expected,  the  surfaces 
of  the  disks  are  considerably  crushed  and  distorted,  but  enough  characteristics  are  visible  to  admit  of  the  above 
specific  description.  The  specimens  have  been  compared  with  the  recent  alcoholics  in  the  collection  of  the  United 
States  National  Museum,  but  no  forms  agreeing  even  remotely  with  the  fossils  were  found.  Both  A.  H.  Clarke  and 
the  writer  are  of  the  opinion  that  the  fossils  belong  to  the  genus  Amphiura,  although,  as  might  be  expected  in 
molds,  some  of  the  diagnostic  characters  are  lacking.  The  species  is  named  in  honor  of  the  Santa  Cruz  quadrangle, 
near  which  the  types  were  obtained. 

Locality. — Hills  immediately  southeast  of  Scott  Valley,  6  miles  north-northeast  of  Santa 
Cruz,  Santa  Cruz  County,  Cal. 

Geologic  Tiorizon. Santa.  Margarita  formation,  middle  or  upper  Miocene. 
Collection. — Stanford  University  (107S);  U.  S.  National  Museum  (165431). 

Class  ECHINOIDEA. 

Subclass  REGULAEIA  ENDOBRANCHIATA. 

Order  CIDAROIDEA. 

Family  CIDARID^. 

Genus  CIDARIS  Leske. 

CiDARis  THOUAEsii  (?)  Valencienncs. 

Cidaris  thouarsii  Valenciennes,  1846,  Agassiz  and  Desor,  Cat.  raisonn^  des  echinodermes,  Soc.  nat.  Ann.,  vol.  6,  v.  326. 
Cidaris  sp.  a  Arnold,  1908,  U.  S.  Nat.  Mus.  Proc,  vol.  34,  pp.  351,  359. 
Cidaris  sp.  a  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  701. 

Description. — This  species,  wliich  Arnold  has  referred  to  under  the  name  of  Cidaris  sp.  a,  is 
regarded  by  H.  L.  Clark  as  probably  C.  thouarsii.     He  says  in  a  letter  quoted  by  Arnold: 

The  wax  cast  [Cidaru  sp.,  a]  is  a  spine  of  a  true  Cidaris  and  very  much  like  many  spines  of  some  individuals  of  the 
species  of  Cidaris  conmion  on  the  west  coast  of  Lower  California,  Mexico,  and  Central  America,  C.  thouarsii.  I  do  not 
think  it  shows  a  single  feature  by  which  it  can  be  distinguished  from  thouarsii,  it  is  certainly  from  the  ancestor  of  that 
species. 

Locality. — Santa  Cruz  quadrangle,  Cal. 

Geologic  horizon. — Monterey  shale,  middle  Miocene. 

Collection. — ^U.  S.  National  Museum. 


180  MESOZOIC    AND    CEjSTOZOIC    ECHIXODEEMATA    OF    THE    UNITED    STATES. 

Subclass  REGUIAKIA  ECTOBRANCHIATA. 
,  Older  DIADEM OIDEA. 

Siztooider  ARBACINA. 
Family  ARBACIIDjE. 

Genus  ECHINOCIDABIS  Duncan. 

EcHiNOCiDAEis  sp.  McCrady. 

Echino-cidaris  sp.  McCrady,  1S55,  in  Tuomey  and  Holmes,  Pliocene  fossils  of  South  Carolina,  PL  II,  figs.  5,  5a. 
Arbacia  sp.  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Description. — ^An  illustration  of  tliis  form  "restored  from  several  fragments"  is  given  by 
McCrady  but  no  description  is  furnished.  Its  generic  relations  are  veiy  questionable  because  of 
doubt  as  to  the  accuracy  of  the  drawing. 

Locality. — South  Carolina. 

Geologic  liorizon. — Miocene  ( ?). 

CoZZec^ion,.  ^Unknown. 

Genus  CCELOPLEUlltrS  Agassiz. 

CcELOPLEUBUS  iMPKOCERXJs  (Conrad). 
Plate  LXXXIV,  figures  4a-c. 

Echinus  improceriis  Conrad,  1843,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  3,  p.  310. 
Psammechinus  improccras  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  \ol.  30,  p.  705. 

Determinative  cTmracters. — Test  large,  circular,  depressed,  concave  below.  Ambulacra 
narrow,  each  with  two  rows  of  primaiy  tubercles  extending  from  peristome  over  ambitus  about 
two-thirds  of  way  from  latter  to  apical  system,  secondary  tubercles  above;  poriferous  zones 
narrow,  slightly  flexuous.  Interambulacra  wide,  the  two  rows  of  primary  tubercles  on  upper 
surface  small.     Peristome  large,  with  slight  brachial  incisions. 

Dimensions. — Diameter  35  millimeters;  height  15  millimeters. 

Description. — This  species  was  first  described  by  Conrad  in  1843.  No  illustration  accom- 
panies the  description,  but  the  species  is  without  doubt  the  form  found  by  the  authors  in  the 
Yorktown  formation  near  the  James  River  and  figured  and  described  in  tliis  monograph.  It 
corresponds  in  all  particulars  to  the  mcomplete  description  which  Conrad  gives  to  it. 

The  test  is  large,  cuxular  and  depressed.  The  slope  of  the  upper  surface  is  very  low  toward 
the  apex.     The  lower  surface  is  concave. 

The  ambulacra  are  narrow,  each  bearing  two  rows  of  prunary  tubercles  which  are  much 
larger  at  the  ambitus  than  on  the  lower  or  upper  surface.  They  cUminish  rapidly  in  size  on  the 
upper  surface  and  about  two-tliirds  of  the  way  to  the  apical  system  become  secondaries  or 
diminish  altogether.  One  or  more  isolated  primaries  also  occur  at  tliis  point  of  disappearance 
with  a  secondary  between.  The  poriferous  zones  are  narrow  and  somewhat  sinuous,  the  pore 
pairs  uniserial. 

The  interambulacra  are  broad  with  four  rows  of  prhnaiy  tubercles  at  the  amibitus  similar 
to  those  of  the  ambulacra.  They  become  smaller,  reduced  in  number,  and  more  or  less  irregularly 
crowded  together  near  the  peristome.  Above  the  ambitus  the  rows  of  primary  tubercles  are 
soon  reduced  to  two  wliich  with  diminished  size  continue  to  the  apical  system.  A  large,  mUiai-y 
median  space  is  found  in  the  upper  portion  of  each  interambulacrum. 

The  apical  system  is  large  but  much  broken  in  the  tj'pe  specimen.  The  peristome  is  large 
with  small  brancliial  incisions.     The  periproct  is  large  and  elongate. 

Localities. — James  River,  near  Smithfield  (type);  J.  T.  Williams's  marl  pit,  Smith  Creek, 
half  a  mile  below  Suffolk,  Va.  (figured  specimen). 

Geologic  horizon. — ^Yorktown  formation,  upper  Pliocene. 

Collection. — ^U.  S.  National  Museum  (166487). 


MIOCENE    ECHINODEEMATA.  181 

CcELOPLEUKUs  SLOANi  Clark,  n.  sp. 

Plate  I.XXXIV,  figures  5a-b. 

Determinative  characters. — Test  moderate  size,  circular,  elevated.  Ambulacra  narrow, 
each  with  two  rows  of  primaiy  tubercles  which  rapidly  diminish  in  size  above  the  aml^itus. 
Interambulacra  with  median  space  on  upper  surface  without  tubercles.  Apical  system  prom- 
inent.    Peristome  small.     Periproct  large,   subpentagonal. 

Dimensions. — Diameter  27  millimeters;  height  15  milluneters. 

Description. — This  species  has  a  test  of  medium  size,  circular  in  ambital  outline  and  much 
elevated.  The  apex  is  liigh  and  the  upper  surface  slopes  regularly  and  rapidly  from  the  ambitus 
to  it.     The  lower  surface  is  concave. 

The  ambulacra  are  narrow,  the  poriferous  zones  being  nearly  straight  and  flush.  Each  am- 
bulacrum has  two  I'ows  of  primary  tubercles  imperforate  and  noncrenulate,  which  are  very  much 
larger  at  the  ambitus  than  above  or  below.  These  tubercles  are  veiy  rapidly  reduced  in  size 
on  the  upper  surface  and  entirely  disappear  or  are  replaced  by  small  secondaries  as  the  apical 
system  is  approached. 

The  interambulacra  have  similar  tubercles  to  those  of  the  ambulacra,  the  two  outer  rows 
only  on  each  area  continuing  to  the  apical  system. 

The  apical  system  is  simple  and  distinct.  The  peristome  is  small  and  the  periproct  large 
and  of  subpentagonal  outline. 

Related  forms. — C.  sloani  is  quite  distinct  from  C.  itnprocerus,  the  oidy  other  Miocene  species 
known  at  the  present  time.  It  is  much  higher  and  has  a  quite  different  distribution  of  the 
primaiy  tubercles. 

Locality. — ^Basticks  Landing,  Great  Peedee  River,  S.  C. 

Geologic  horizon. — ^Miocene. 

Collection.— \J.  S.  National  Museum  (166488). 

Suborder  ECHININA. 
Family  TRIPLECHINID.E. 

Genus  PSAMMECHINTJS  Agassiz. 
PSAMMECHINUS    PHILANTHEOPUS    (Conrad). 

Plate  LXXXIV,  figures  6a-c. 

Echinus  philanihropus  Conrad,  1843,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  1,  p.  310. 

Echinus  ruffini  Forbes,  1845,  Geol.  See.  London  Quart.  Jour.,  vol.  1,  p.  426,  figs.  a-d. 

Echinus  ruffini  Forbes,  1845,  Geol.  Soc.  London  Proc,  vol.  4,  p.  560,  text  figs. 

Echinus  jjhilanthropu-s  Conrad,  1846,  Am.  Jour.  Sci.,  2d  ser.,  vol.  1,  No.  2,  p.  220. 

Psammechinus  ruffini  Desoi,  1S5S,  Synopsis  fehinides  fossiles,  p.  121. 

Echinus  ruffini  Emmons,  1858,  Agriculture  eastern  counties:  North  Carolina  Geol.  Survey,  pp.  306,  307,  figs.  239a-d . 

Psammechinus  philanthropus  Jleek,  1864,  Check  list,  Miocene,  p.  2. 

Psammechinus  ruffini  Stefaniui,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  75. 

Determinative  characters. — Test  small,  subhemisphcrical,  tumid  at  the  ambitus,  somewhat 
depressed  above,  nearly  flat  below.  Ambulacra  with  two  main  rows  of  primary  tubercles  extend- 
ing from  peristome  to  apical  system,  with  a  thick  median  row  a  portion  of  distance,  poriferous 
zones  narrow;  joore  pairs  in  triplets  in  oblique  rows.  Interambulacra  \vith  four  regular  and  two 
median  somewhat  irregular  rows  of  subequal  primary  tubercles  at  ambitus,  the  latter  reduced 
toward  peristome  and  apical  system.     Peristome  rather  wide,  branchial  incisions  distinct. 

Description. — This  species  which  was  described  by  Conrad  in  1843  from  material  secured 
near  Smithiield,  Va.,  was  described  by  Forbes  two  j'cars  later  as  E.  ruffini.  The  test  is  small 
and  subhemispherical,  with  a  nearly  circular  ambital  outlme.  It  is  tumid  at  the  ambitus,  some- 
what depressed  above  and  nearly  flat  below,  with  a  slight  depression  near  the  peristomial  margin. 

The  ambulacra  are  rather  narrow,  the  median  portion  of  each  area  being  covered  with  two 
main  rows  of  primary  tuberclss,  imperforate  and  mmcrenulate,  which  extend  from  the  peristome 


182  MESOZOIC   AND   CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

to  the  apical  system.  A  third  row  lies  between  the  other  two,  and  in  the  larger  forms  there  are 
additional  tubercles  that  are  best  developed  near  the  ambitus  and  do  not  reach  either  peristome 
or  apical  system.  The  poriferous  zones  are  narrow,  and  the  pore  pairs  are  foimd  in  triplets 
arranged  obliquely. 

The  interambulacra  are  covered  with  tubercles  similar  to  the  ambulacra.  Six  or  more  rows 
of  primary  tubercles  occur,  four  being  very  regular  and  two  reaching  all  the  way  from  the  peri- 
stome to  the  anal  system.  The  remaining  two  rows  and  in  some  cases  additional  rows  or  extra 
subequal  tubercles  are  chiefly  developed  at  the  ambitus.  The  entire  surface  of  both  inter- 
ambulacra and  ambulacra  are  thickly  studded  with  so  many  tubercles  of  about  the  same  size  as 
to  give  it  a  very  uniform  appearance. 

The  apical  system  is  small.  The  peristome  is  rather  wide  with  moderately  distinct  brancliial 
incisions. 

Localities. — James  River  and  York  River  (type  and  figured  specimen),  Va. 

Geologic  Jionzon. — Yorktowai  formation,  upper  Miocene. 

Collections. — Johns  Hopkins  University  (T  1001);  Academy  of  Natural  Sciences  of  PliUa- 
delphia. 

PsAMMECHiNUS  EXOLETUS  ]\IcCrady. 

PsammecMnus  exoletus  McCrady,  1S57,  in  Tuomey  and  Holmes,  Pliocene  fossils  of  South  Carolina,  p.  4,  PL  II,  fig.  6. 
Psammechinus  exoletus  Meek,  1864,  ('heck  list,  Pliocene,  p.  2.     . 
PsammecMnus  exoletus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Description. — The  fragment  briefly'  described  and  figured  by  McCrady  is  the  only  material 
so  far  as  kno-wn  that  has  been  found  representing  this  species.  The  description  and  figure  are 
insufficient  to  separate  with  certainty  this  form  from  other  species. 

Locality. — Goose  Creek,  S.  C.     (Smith.) 

Geologic  hori.zon. — Duplin  marl,  upper  Miocene. 

Collection . — ^Unknown . 

Subclass  IRREGULARIA. 

Order  GNATHOSTOMATA. 

Suborder  CLYPEASTRINA. 

Family  FIBULARIID^. 

Genus  SISMONDIA  Desor. 

SiSMONDiA  (?)  ARNOLDi  T\vitchell,  n.  sp. 

'  Plate  LXXXV,  figures  la-b. 

Astrodapsis  sp.  indet.  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  396,  p.  30,  PI.  XXMII,  fig.  5,  5a. 
Astrodapsis  sp.  indet.  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  703. 

Descnption  and  determinative  cTmracters. — Tliis  little  echuioid,  one  of  the  smallest  occurring 
m  the  Tertiary  deposits  of  the  Pacific  coast,  was  first  figured  but  not  described  by  Ralph  Arnold, 
of  the  U.  S.  Geological  Survey,  in  whose  honor  the  species  is  named.  The  test  is  veiy  small, 
being  less  than  half  an  inch  in  diameter.  In  marginal  outline  it  is  suboval,  with  a  slight  tend- 
ency toward  the  subpentagonal,  the  anterior  end  being  slightly  angulated,  the  posterior  broader 
and  rounded.  The  whole  form  is  much  depressed,  slightly  convex  above,  slightly  concave  below; 
margin  of  moderate  thickness.  Apex  central.  The  ambulacral  j^etals  are  long,  reachmg  the 
margin;  .poriferous  zones  narrow,  diverging  in  straight  Imes  from  apex  to  margin;  pores  of  both 
rows  round.  The  whole  test  is  covered  mth  small  but  rather  conspicuous  tubercles.  The  apical 
system  is  central,  with  a  conspicuous  tumid  madreporite.  The  other  details  could  not  be  made 
out  on  the  specimen.  The  peristome  is  relatively  large,  central,  subcircular  to  subpentagonal. 
The  ambulacral  grooves  appear  as  rather  well  defined,  simple,  straight  lines  for  a  short  distance 
out  from  the  peristome,  beyond  which  they  become  obscure.  The  peripi'oct  is  very  small,  circu- 
lar, inframarginal,  almost  marginal. 

Dimensions. — Length  10.5  millimeters;  width  9.5  millimeters. 


MIOCENE   ECHINODEKMATA.  183 

Related  forms . — S .  arnoldi  vesembles  Sismondia  (?)  coalinffaensis  undScuteUa  (?)  merriami,        ' 
but  differs  from  both  in  having  petals  extending  to  the  margin,  with  straight,  diverging  porifer- 
ous zones. 

Locality. — Four  miles  southeast  of  northwest  end  of  Kettleman  Hills,  Coalinga  district, 
California. 

Geologic  horizon. — Etchegoin  formation,  upper  ^Miocene  and  lower  Pliocene  ( ?) . 

Collection.— V.  S.  National  Museum  (16553S). 

Sismondia(?)  coalingaensis  Twtchell,  n.  sp. 
Plate  LXXXV,  figures  2a-c. 

Description  and  determinative  characters. — The  test  of  this  species  is  very  small,  rarely  ex- 
ceeding one-half  inch  in  length.  In  marginal  outline  it  is  suboval  to  subovate,  broader  posteri- 
ori}' than  anterioid}'.  The  whole  form  much  depressed,  shghtly  tumid  centrally;  margin  rather 
thin.     Apex  sul)central  or  shghtly  excentric  posteriorly.     Lower  surface  concave. 

The  ambulacral  petals  are  subelliptical  in  outline,  extending  a  little  more  than  halfway  to 
the  margin;  the  posterior  pair  shorter  than  the  anterior  pair:  pores  round,  pairs  of  pores  con- 
jugated.    The  whole  test  is  covered  M"ith  small  but  conspicuous  tubercles,  scattered  irregularly. 

The  apical  system  is  subcentral  or  slightly  excentric  posteriorly,  coincident  \\\i\\  the  apex. 
The  details  could  not  be  made  out  on  the  specimen  studied. 

The  peristome  and  ambulacral  grooves  could  not  be  made  out.  The  periproct  is  small, 
inframarginal,  almost  marginal. 

Dimensions. — Length  12  milUmeters;  width  10  millimeters;  height  2  milhmcters. 

Related  forms. — <?.  coalingaensis  resembles  Sismondia  (?)  arnoldi  and  Scutella  (?)  m,erriami. 
From  the  former  it  differs  in  having  shorter,  subelliptical  petals  and  from  the  latter  in  lacking 
the  tumid  petals  and  in  having  a  more  longitudinally  oval  marginal  outhne. 

Locality. — Jacahtos  Creek,  half  a  mile  east  of  KJreycnhagen's,  Coahnga  district,  Cahfornia. 

Geologic  horizon. — Etchegoin  formation,  upper  Miocene  and  lower  Pliocene  (?). 

Collection. — LT.  S.  National  Museum  (16.5717). 

Family  SCUTELLID^. 

Gonus  SCTJTEIiLA  Lamarck. 
Sc^TTELLA  ANDERsoNi  Twitchell,  n.  sp. 
Plate  LXXXV,  figures  3a-cl. 
Scutella  sp.  A.,  F.  M.  Anderson  1905,  California  Acad.  Sci.  Proc,  3d  ser.,  Geology,  vol.  2,  No.  2,  p.  193,  PI.  XIII.  fig.  8. 

Determinative  characters. — Test  small;  suboval  to  broadly  subovate,  broadest  posteriorly; 
margin  thin,  more  so  posteriorly  than  anteriorly,  with  rather  pronounced  notches  opposite  the 
posterior  petals;  the  whole  form  greatly  depressed,  the  upper  surface  ridged  along  the  longitu- 
dinal median  hne,  sloping  rather  steeply  away  from  the  ridge  to  the  side  edges;  apex  excentric 
anteriorly;  under  surface  slightly  concave  longitudinally.  Apical  system  decidedly  excentric 
anteriorly,  about  coincident  with  the  apex.  Posterior  ambulacral  petals  slightly  longer  than  the 
anterior  paired  petals  which  are  slighth'  longer  than  the  odd  petal.  Peristome  excentric  anteri- 
orly.    Periproct  very  small,  supramarginal. 

Dimensions. — Length  25  miUimeters;  M-idth  25  millimeters;  height  5  millimeters. 

Description. — This  interesting  species  was  liriefly  described  and  figured  in  1905  by  F.  M. 
Anderson  but  was  not  given  a  specific  name.  It  is  here  named  in  honor  of  Mr.  Anderson.  The 
test  is  small,  ranging  from  less  than  a  half  to  slightly  more  than  an  inch  in  diameter.  In  mar- 
ginal outline  it  is  suboval  to  broadly  subovate;  broadest  posteriorly,  usualh'  about  as  long  as 
wide.  The  margin  is  thin,  more  so  posteriorly  than  anteriorly,  with  rather  pronounced  notches 
opposite  the  posterior  petals  and  sometimes  with  faintly  defined  notches  opposite  the  anterior 
paired  petals.  The  whole  form  is  greatly  depressed;  the  upper  surface  having  a  more  or  less 
weU  defuied  ridge  extenduig  along  the  longitudinal  median  line  and  involving  the  otUl  petal. 


184  MESOZOIC    AND    CENOZOIC    ECHINODERMATA    OF    THE    UNITED    STATES. 

the  inner  ends  of  the  other  petals,  and  the  inner  portion  of  the  posterior  interambulacrum;  from 
the  median  ridge  the  surface  slopes  at  first  steeply  then  gi-adually  away  to  the  side  edges.  The 
under  surface  is  slightly  concave  longitudinally.  The  apex  is  excentric  anteriorly,  at  the  highest 
point  of  the  median  ridge. 

The  ambulacral  areas  are  rather  naiTow;  the  dorsal  portions  petaloid.  The  petals  are 
moderate  in  size,  subelliptical,  extending  more  than  halfway  to  the  margin,  open  at  the  ends,  the 
odd  petal  more  ^\'idely  open  than  the  others.  The  poriferous  zones  are  relatively  A\-ide,  though 
shghtly  less  so  than  the  interporiferous  areas;  pores  oval,  pairs  of  pores  conjugated. 

The  interambulacral  areas  are  rather  broad  with  the  exception  of  the  odd  posterior  area, 
which  is  narrow.     The  surface  of  the  test  is  covered  ^^^th  small  uniform  tubercles. 

The  apical  sj'stem  is  decidedly  excentric  anteriorly,  about  coincident  \nth  the  apex.  There 
is  a  large,  subcircular  madreporite,  four  large  genital  pores,  of  which  the  anterior  pair  are  some- 
what nearer  together  than  the  posterior  pair,  and  five  small  radial  plates  each  perforated  by  a 
minute  pore. 

The  peristome  is  excentric  anteriorly.  The  character  of  the  ambulacral  furrows  can  not 
be  made  out  on  the  specimens  studied. 

The  periproct  is  very  small,  circular  and  supramarginal,  almost  marginal. 

Related  forms. — S.  andersoni  is  readily  distinguished  from  all  other  American  scuteUas 
by  its  longitudinally  ridged  upper  surface,  its  longitudinally  concave  lower  surface,  and  its 
pronounced  marginal  notches  opposite  the  posterior  paired  petals. 

Localities. — West  of  Coahnga  (Anderson),  and  Devils  Den  district,  Kern  County  (figured 
specimen),  Cal. 

Geologic  horizon. — Tejon  formation,  upper  Eocene;  Vaqueros  sandstone,  lower  Miocene. 

Collections. — U.  S.  National  Museum  (165719);  Cahfornia  Academy  of  Sciences. 

SCUTELLA    FAIRBANKSI    Pack. 

Plate  LXXXV,  figures  4-6. 

IScutella  gabhi  Merriam,  1S99,  California  Acad.  Sci.  Proc,  3d  ser.,  Geology,  vol.  1,  No.  5,  p.  168,  PI.  XXII,  figs.  5,  5a. 
Scutdlafairbanksi{UeTTiAm,US.)  Arnold,  1907,  U.  S.Nat.Mus.  Proc,  vol  32,  p.  542,  PI.  XLII,  flg.  3,  PI.  XLIII,  fig. 

3.     No  description. 
Scutclla/airbanlcsi  Eldridge  and  Arnold,  1907,  U.  S.  Geol.  Survey  Bull.  309,  pp.  13,  17,  230,  232,  PI.  XXIX,  fig.  3, 

PI.  XXX,  fig.  3.     No  description. 
Scutdla  fairbanksi  Pack,  1909,  Univ.  California  Dept.  Geology  Bull.,  vol.  5,  No.  18,  pp.  276-277,  PI.  XXIII,  fig.  1. 
?Scutdla  mciriami  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  396,  PL  VI,  fig.  4.     Figiire  only. 

'!Scutdla  merriami  Arnold  and  R.  Anderson,  1910,  U.  S.  Geol.  Survey  Bull.  398,  PI.  XXVIII,  fig.  4.     Figure  only. 
Echinarachnius fairbanksi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  703. 

Determinative  characters. — Test  medium  in  size;  subcircular,  transversely  oval  or  broadly 
subovate,  slightly  broader  than  long;  margin  markedly  thin  and  faintly  vmdulating,  submarginal 
area  wide;  the  whole  form  greatlj^  depressed,  the  upper  surface  rising  gradually  and  very  gently 
from  the  margin  to  the  low  central  or  subcentral  apex;  under  surface  flat  or  nearly  so.  Apical 
system  central  or  slightly  excentric  anteriorly  and  about  coincident  with  the  apex.  Ambula- 
cral petals  relatively  short,  subequal  in  size,  subsymmetrical  as  a  group;  the  odd  petal  differing 
from  tlie  rest  in  having  its  inner  row  of  pores  diverging  gradually  to  the  end,  which  is  wide  open, 
much  more  so  than  in  the  other  petals.  Peristome  central  or  subcentral;  main  ambulacral 
furrows  deep  and  probably  simple  and  straight  for  most  of  the  distance  to  the  margin,  then 
branchmg.     Periproct  very  small,  supramarginal. 

Dimensions. — Specimen  A  (type):  Length  53  millimeters;  width  49  millimeters  (Pack). 
Specimen  B:  Length  3-3  millimeters;  width  36  millimeters. 

Description. — This  new  Californian  Scutella  has  a  test  which  is  of  medium  size,  ranging 
from  about  1  to  2^  inches  in  diameter.  In  marginal  outline  it  is  somewhat  variable,  being 
sometimes  subcircular,  sometimes  transversely  oval,  sometimes  broadly  subovate.  The  margin 
is  markctUy  thin  and  faintly  undulating,  submarginal  area  wide.  The  whole  form  is  greatly 
depressed;  the  upper  surface  rising  gradually'  and  very  gently  from  the  margin  to  the  low,  central 
or  subcentral  apex.     The  under  surface  is  flat  or  nearly  so. 


MIOCEKE    ECHINODEEMATA.  185 

The  ambulacral  areas  are  rather  wide  at  the  margin,  where  they  equal  or  exceed  the  inter- 
ambulacral  areas,  witlening  rapidly  from  the  ends  of  the  lateral  and  posterior  petals,  less  rapidly 
from  the  odd  petal;  dorsal  portions  petaloid.  The  petals  are  relatively  short,  almost  symmetrical 
as  a  group,  almost  equal  in  size,  extending  from  one-half  to  almost  two-thirds  the  way  to  the 
margin,  all  but  the  odd  petal  subelhptical  in  outline,  tending  to  close  at  the  ends;  the  odd  petal 
noticeably  differs  from  the  rest  in  form,  having  its  inner  rows  of  pores  diverging  gradually  to  the 
end,  which  is  wide  open,  much  more  so  than  that  of  the  other  petals.  The  poriferous  zones  are 
relatively  -vvide;  pores  oval;  pairs  of  pores  conjugated;  interporiferous  areas  of  the  anterior 
paired  and  posterior  petals  rather  narrow,  not  much  wider  than  the  poriferous  zones,  that  of  the 
odd  petal  considerably  wider,  especially  at  the  outer  end  of  the  petal.  Several  pairs  of  pores,  in 
strongly  diverging  rows,  extend  beyond  the  ends  of  the  petals. 

The  interambulacral  areas  are  all  rather  narrow  between  the  petals,  broad  from  about  oppo- 
site the  ends  of  the  petals  to  the  margin.  The  surface  of  the  test  is  covered  with  small  uniform 
tubercles,  which  are  somewhat  larger  on  the  under  surface,  especially  near  the  peristome. 

The  apical  system  is  central  or  sHghtly  excentric  anteriorly  and  about  coincident  with  the 
apex.  The  details  are  obscure  on  the  specimens,  but  there  arc  four  large  genital  pores  of  which 
the  two  anterior  are  nearer  together  than  the  posterior  pair. 

The  peristome  is  central,  or  subcentral,  shghtly  depressed;  ambulacral  furrows,  according  to 
Pack,  are  "deep  and  traceable  to  the  margin,"  where  thej-  '"show  asUght  tendency  to  branch." 
On  the  specimens  studied  they  are  not  well  shown. 

The  periproct  is  very  small,  supramarginal;  sometimes  located  at  a  distance  from  the  edge 
equal  to  its  own  diameter. 

Related  forms. — S.fairbanksi  is  most  closely  related  to  S.  gabhi  (Remond)  Merriam,  Init  dif- 
fers from  it,  according  to  Pack,  in  "  attaining  a  greater  size,  in  having  a  slightly  undulating  mar- 
ginal outline,  in  having  deeper  and  better  marked  fuiTows  on  the  actinal  surface,  and  in  having 
the  anal  pore  entirely  upon  the  upper  surface."  S.  fairianJcsi  is  also  allied  to  Dendraster 
intcrliTieatus  and  D.  oregonensis,  but  may  lie  easily  separated  from  both  by  its  more  central 
apical  system,  shorter  and  more  equal  petals,  and  wider  marginal  area.  It  also  differs  from 
D.  oregonensis  in  having  the  posterior  poriferous  zones  of  its  paired  petals  curving. 

The  specimen  figured  by  Arnold  as  ScuteUa  merriami  was  probably  a  young  specimen  of 
S.fairhanlcsi. 

Localities. — Near  Torrey  Canyon  wells,  southwest  of  Piru,  Ventura  County,  Cal.  (Arnold); 
Sespe  Canj'on,  Ventura  County,  Cal.  (Pack,  Arnold). 

Geologic  Tiorizon. — Vaqueros  formation,  lower  IVIiocene. 

Collections.— v.  S.  National  Museum  (164963,  B,  C);  University  of  California  (A). 

ScrxELLA   (?)   MERRIAMI   (Anderson) . 
Plate  LXXXV,  figures  7a-c,  8a-b. 

Astrodapsis  merriami  F.  M.  Anderson,  1905,  California  Acad.  Sci.  Proc,  3il  ser.  Geology,  vol.  2,  No.  2,  pp.  193-194,  PI. 

XIV,  figs.  33,  34. 
ScuteUa  merriami  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  396,  p.  18. 
IScutella  merriami  Arnold,  1909,  figure,  U.  S.  Geol.  Survey  Bull.  396,  PL  VI,  fig.  4. 
ScuteUa  merriami  Arnold  and  R.  Anderson,  1910,  U.  S.  Geol.  Sur-\-ey  Bull.  398,  pp.  85,  86,  87. 
^ScuteUa  merriami  Arnold  and  R.  Anderson,  1910,  figure,  U.  S.  Geol.  Survey  Bull.  398,  PI.  XXVIII,  fig.  4. 
Sismondiamerriami  Steianiai,  1911,  Soc.geol.  italianaBolL,  vol.  30,  p.  702. 

Description. — This  Uttle  echinoid  was  first  described  and  figured  by  F.  II.  Anderson  in  1905. 
Its  button-Uke  appearance  and  its  abimdance  m  certain  deposits  in  the  Coalinga  district  of  Cali- 
fornia have  led  to  these  deposits  being  designated  Button  beds.  The  AVTiter  has  had  about  20 
specimens  from  the  Button  beds  available  for  stud}',  most  of  which  probably  belong  to  this 
species;  but  most  of  them  were  in  poor  condition  and  as  the  type  could  not  be  secured  for  com- 
parisons the  description  of  F.  M.  Anderson  is  here  given  verbatim: 

Disk  small,  circular,  depressed;  margin  only  slightly  notched  at  the  ambulacral  extremities;  apex  central,  only 
slightly  elevated,  star  symmetrical,  petals  equal  but  not  reaclimg  the  margin  of  the  disk,  and  slightly  elevated;  anal 


186  MESOZOIC    AXD    CEXOZOIC    ECHINODEEMATA    OF    THE    ITNIIED    STATES. 

pore  marginal;  ambulacral  furrows  of  inferior  surface  straight  and  simple.  The  largest  specimens  have  a  diameter  of  IJ 
inches,  though  the  usual  size  is  three-foiu-ths  of  an  inch.  The  disk  is  thin  and  flattened  but  sliowa  a  decided  tendency 
to  form  elevated  stars  on  the  upper  stirface. 

The  ^vl■iter's  study  of  the  specimens  from  the  Button  ])eds  ahead}-  referred  to  suggests  a  few 
comments  in  connection  with  this  description.  The  size  of  the  specimens  studied  ranged  from  8 
to  15  miUimeters  in  diameter.  The  marginal  outline  was  usually  circular,  Init  sometimes  longi- 
tudinally oval.  The  marginal  notches  are  often  hardly  discernible.  The  petals  extend  from 
hah  to  two-thirds  the  way  to  the  margin.  In  some  specimens  the  petals  were  practically  flush 
with  the  surface  and  in  some  were  slightly  tumid.  In  some  the  poriferous  zones  of  all  the  petals 
diverge  continuously  and  are  \nde  open  at  the  ends,  though  the  odd  petal  is  somewhat  more 
widely  open  than  the  rest;  in  others  those  of  all  but  the  odd  petal  are  partly  closed,  as  in  the 
form  figured  by  Anderson.  In  the  form  figured  by  Arnold  (which  has  been  examined  by  the 
writer)  the  poriferous  zones  of  aU  but  the  odd  petal  diverge  for  about  half  their  length,  then  con- 
verge to  a  less  degree  so  that  at  then-,  ends  they  are  only  slightly  nearer  together  than 
midway,  those  of  the  odd  petal  diverging  continuously  to  their  ends,  where  they  are  far  apart, 
the  inner  hues  of  pores  forming  a  well-defined  V.  In  view  of  the  variations  indicated  it 
seems  probable  that  among  the  small  echinoids  of  the  Button  beds  there  are  several  forms, 
possibly  distinct  species,  which  closely  resemble  each  other  in  general  appearance,  while  differing 
in  details.  The  lines  between  these  forms  can  only  be  drawn  by  one  who  has  access  to  the  tvpe 
and  to  an  extensive  series  of  good  specimens.  However,  the  ^mter  is  of  the  opinion  that,  in  view 
of  Anderson's  significant  remark  that  the  test  "shows  a  decided  tendency  to  form  elevated  stars 
on  the  upper  surface, "  the  small  button  like  forms  with  shghtly  tumid  petals  are  most  tj-pical  of 
the  species  S.  mirriami.  Some  of  the  larger  specimens  assigned  to  S.  mernami — such  as  the  one 
figured  by  Arnold — strongly  resemble  Scutella  fairlanlcsi  and,  with  further  collecting  and  com- 
parative study  With  the  types  of  the  forms  involved  in  hand,  may  prove  to  be  young  specimens 
of  that  species.  Aside  from  its  smaller  size,  the  only  important  apparent  difference  between 
Arnold's  figured  form  and  S.  fairbanlsi  is  that  the  periproct  is  exactly  marginal,  visible  from 
above  and  below;  but  it  may  be  found  that  S.fairlanlcsi,  which  is  somewhat  variable  in  regard  to 
this  feature,  may  varj'  enough  to  include  forms  with  a  marginal  periproct. 

There  is  some  doubt  in  regard  to  the  generic  position  of  the  present  species.  There  seems  to 
be  no  good  ground  for  placing  it  in  the  genus  Astrodapsis,  as  it  lacks  the  depressed  apical  system 
and  deeply  impressed  interambulacral  areas  characteristic  of  that  genus.  Anderson  says  that 
the  ambulacral  furrows  are  straight  and  simple,  which,  if  true,  would  suggest  placing  it  in  the 
genus  Sismondia,  but  on  the  other  hand  in  the  figure  of  the  under  surface  given  by  Anderson  the 
furrows  appear  to  be  simple  and  straight  for  about  two-thirds  of  the  way  to  the  margin  and  then 
bifurcate  symmetrically,  which  fact  points  toward  the  genus  Scutella.  It  is  not  improbable  that 
both  genera  may  be  represented.  The  ambulacral  furrows  are  not  discernible  upon  the  speci- 
mens studied  by  the  writer,  and  the  form  is  therefore,  for  the  present,  placed  doubtfully  in  the 
genus  Scutella. 

Localities. — Tar  Springs,  Ki-eyenhagen's  and  Temblor,  Mount  Diablo  Range,  CaUfornia 
(F.  W.  Anderson) ;  Garza  Creek  gorge  in  Reef  Ridge,  C'anoas  Canyon,  near  Hugo  Kreyenhagen's 
place,  and  8^  miles  north  of  Coalinga,  all  in  the  Coahnga  district,  Cahfornia  (Arnold) ;  Wagon- 
wheel  Mountain,  Devils  Den  district,  Kern  County,  Cal.  (Arnold). 

Geologic  horizon. — Yacpieros  formation,  lower  Miocene.  Occurs  in  the  Button  beds,  which 
are  near  the  middle  of  the  formation. 

CoUections.—V.  S.  National  ]\Iuseum  (165584,  B;  165716,  A);  Cahfornia  Academy  of 
Sciences;  F.  M.  Anderson. 

Scutella  xorrisi  Pack. 

Plate  LXXXV,  figure  9. 

Scutella  (?)  norrisi  Pack,  1909,  fniv.  California  Dept.  Geologj'  Bull.,  vol.  5,  Xo.  18,  pp.  277-278,  PL  XXIII,  fig.  3. 
Echinarachnius  norrisi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  703. 

Descriptioji. — Since  no  opportunity  has  been  had  of  studying  any  specimen  of  this  species 
the  description  of  Pack  is  given  verbatim: 


MIOCENE    ECHINODEEMATA.  187 

Test  siibcircular  in  general  outline,  with  deep,  broad,  marginal  notches  in  the  edges  of  the  ambulacral  areas.  The 
two  posterior  notches  are  much  deejier  tlian  are  the  anterior  ones,  and  truncate  the  posterior  interambulacral  space  on 
either  side  of  the  median  line,  shaping  the  posterior  end  of  the  test  into  a  prominent  process.  The  test  when  viewed 
from  above  lias  a  leaf- like  appearance.  Test  much  depressed,  edges  markedly  tliin,  abactinal  surface  very  slightly 
arched,  apex  central;  actinal  surface  fiat  or  gently  concave.  Mouth  central,  slightly  sunken;  ambulacral  furrows 
poorly  shown  in  the  specimens  examined,  but  eT.ddently  branch  but  little,  if  at  all.  Main  ambulacral  grooves  continue 
from  the  mouth  to  the  margin,  entering  the  marginal  notches.  Anal  pore  small,  inframarginal.  Ambulacral  star  cen- 
tral.    Petals  extend  about  three-fourths  the  distance  to  the  margin  and  not  entirely  closed  at  the  ends. 

Dimensions. — Longitudinal  diameter,  55  millimeters. 

As  only  a  single  figure  of  this  form  is  given  by  Pack/  and  as  that  too  is  one  of  the  under  sur- 
face of  a  weathered  specimen,  it  is  hardly  possible  to  discuss  the  form  intelUgently.  However, 
it  mtij  be  said  that  the  marginal  outline,  with  its  five  large  ambulacral  notches  alternatmg  with 
broad,  blunt,  rounded  projections  difl'erentiates  the  form  from  all  other  known  Californian  echi- 
noids.  From  the  description  and  figure  the  form  appears  to  be  a  Scutella.  The  resemblance  of 
the  present  species  to  Astrodapsis  whitneyi  which  Pack  remarks  upon  in  connection  with  his 
description  of  A.  antiselU  is  but  a  slight  one,  as  the  notches  of  A.  whitneyi  are  not  nearly  as  large. 

Localities. — Five  miles  northwest  of  the  Stone  Canyon  coal  mine,  Monterey  County,  and  at 
San  Juan  River  near  La  Panza,  San  Luis  Obispo  Countj-,  Cal. 

Geologic  horizon. — Vacjueros  formation,  lower  Miocene. 

Collection. — University  of  Cahfornia. 

Scutella  aberti  Conrad. 

Plate  LXXXVI,  figures  la-b;  Plate  LXXXVII,  figures  la-d. 

Scutella  aberti  Conrad,  1842,  Nat.  Inst.  Promotion  Sci.  Proc,  2d  Bull.,  p.  194,  no  figure. 

Scutella  alberli  Bronn,  1848,  Index  palseontologicus,  vol.  1,  p.  1125,  vol.  2,  p.  196. 

Scutella  alberti  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

Scutella  alberti  Dall,  1892,  U.  S.  Geol.  Survey  Bull.  84,  p.  52. 

Scutella  aberti  Clark,  1904,  Maryland  Geol.  Survey,  Miocene,  p.  432,  PI.  CXXIX,  figs.  2,  2a,  and  PI.  CXX,  figs,  la, 

lb,  2a,  2b. 
Scutella  aberti  Clark,  1906,  Maryland  Geol.  Sui-vey  Kept.,  vol.  6,  p.  258,  PL  XXII,  fig.  17. 
Scutella  aberti  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  705. 

Determinative  characters. — Test  large  to  very  large,  subcircular  to  subcjuadrate  in  marginal 
outhne,  the  whole  form  much  depressed,  less  so  within  the  large  jjetaloidal  area  where  it  rises  in 
the  form  of  a  low,  broad  mound  whose  flattened  summit  is  excentric  anteriorly,  margin  relatively 
thin,  with  three  large,  broad  notches  in  the  posterior  border,  between  which  the  test  extends  in 
the  form  of  two  large,  broad,  blunt  projections;  under  surface  flat.  Ambulacral  petals  very 
large,  subspatulate,  extendmg  more  than  two-thirds  the  way  to  the  margin.  Apical  system 
slightly  excentric  anteriorly  but  less  so  than  the  apex.  Peristome  small,  subpentagonal,  ambu- 
lacral furrows  simple  and  straight  for  a  short  distance  from  the  peristome,  then  forking,  the 
branches  proceedmg  somev/hat  smuously  and  divergingly  to  the  margin.  Periproct  very  small, 
subcircular,  inframarginal,  near  the  head  of  the  pouited  central  notch  in  the  posterior  border. 

Dimensions. — Length  120  millimeters;  width  121.5  milhmeters;  height  14  millimeters. 
The  largest  specimen  examined  was  178  millimeters  in  diameter. 

Description. — This  species,  the  largest  of  American  Scutellas,  was  first  reported  in  1842  by 
Conrad,  who  described  but  did  not  figure  it,  and  who  named  it  after  Col.  J.  J.  Abert,  of  Washing- 
ton, D.  C.  It  was  first  figured  by  Clark  in  1904.  The  form  has  been  but  little  known  owing  to 
its  limited  distribution  and  to  the  obscure  and  out  of  the  way  character  of  the  publication  in 
which  Conrad's  description  was  published.  Perfect  specimens  are  rare;  imperfect  ones  and 
fragments  are  very  abundant  in  the  thin  bed  in  which  it  occurs  and  to  which  it  appears  to  be 
restricted.     It  is  not  known  positively  to  occur  outside  of  Maryland.     Several  authors  have 

1  Since  the  above  description  was  written  Paclc  lias  publislied  additional  details  regarding  5.  norrisi,  based  on  recently  discovered  material 
(Univ.  California  Dept.  Geology  Bull.,  vol.  7,  No.  13,  pp.  299-300,  PI.  XV,  fig.  1).  The  new  material  establishes  on  firm  foundation  this  new 
species,  which  is  unlike  all  other  California  scutellid  forms. 


188  MESOZOIC    AND    CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

given  the  name  of  the  form  as  S.  alberfl  instead  of  S.  aherti,  as  it  should  be.  The  test  is  large  to 
very  large  in  size,  ranging  from  90  milUmeters  to  about  ISO  milhmeters  in  diameter.  In  mar- 
ginal outline  it  is  subcircular  to  subquadrate,  broader  posteriorly  than  anteriorly,  sometimes 
very  noticeably  so.  The  whole  form  is  much  dejiressed  although  more  so  around  the  margin, 
within  the  large  area  covered  by  the  ambulacral  petals  it  rises  in  the  form  of  a  low  broad  gently 
rounded  mound  which  varies  in  height  from  about  -i  to  about  |  inch,  and  the  summit  of  which  is 
flattened  and  excentric  antei'ioi'ly.  The  margin  of  the  test  is  relatively  thin  and  undulating; 
with  a  faint,  broad,  shallow  curved  notch  opposite  each  of  the  three  anterior  petals,  two  large, 
broad,  deep,  curved  notches  opposite  the  posterior  pair  of  petals  and  one  large,  broad,  deep, 
pointed  notch  in  the  middle  of  the  posterior  edge.  Between  the  large  central  notch  and  each 
of  the  large  curved  notches  the  test  extends  in  the  form  of  a  large,  broad,  blunt  projection;  the 
two  projections  and  three  large  notches  together  forming  the  whole  posterior  border  of  the  test. 
The  under  surface  is  flat.  The  apex  is  decidedly  excentric  anteriorly,  at  the  summit  of  the 
tumid  central  area. 

The  ambulacral  areas  are  narrow  m  the  petaloid  region,  but  xory  broad  in  the  niargina 
region,  where  they  are  considerably  wider  than  the  interambulacral  areas.  The  dorsal  portions 
of  the  ambulacra  are  petaloid.  The  petals  are  very  large,  subequal  in  length,  the  posterior  pair 
being  somewhat  longer  than  the  others;  subspatulate  to  Indian-club  shape  in  form;  nearly 
closed  at  the  ends;  extendmg  more  than  two- thirds  the  way  from  the  center  to  the  margin. 
The  poriferous  zones  are  wide,  wider  than  the  interporiferous  areas;  the  inner  row  of  pores  oval, 
outer  row  slithke,  pairs  of  pores  conjugated,  the  groove  lines  continuing  beyond  the  inner  row  of 
pores  to  the  center  of  the  mterporiferous  areas,  and  the  spaces  between  the  grooves  very  narrow. 

The  interambulacral  ai"eas  are  broad  near  the  ends  of  the  petals,  but  become  narrower  toward 
both  center  and  margin.  The  plates  are  polygonal  and  are  very  large,  especially  those  on  the 
imder  surface.  Single  plates  are  often  found  in  a  more  or  less  weathered  condition  showmg  on 
both  their  upper  and  under  surfaces  numerous  grooves  and  ridges.  The  whole  surface  of  the  test 
is  covered  with  small  uniform  tubercles  which  are  slightly  larger  on  the  under  surface. 

The  apical  system  is  relatively  large,  sHghtly  excentric  anteriorly,  on  the  flattened  surface 
posterior  to  the  apex  of  the  test.  The  madreporite  is  relatively  large,  subpentagonal,  occupying 
the  larger  part  of  the  area  covered  by  the  system  and  flush  with  the  surface.  There  are  five 
small  genital  pores  near  the  points  of  the  madreporic  pentagon  and  five  small  triangular  radial 
plates  each  perforated  by  a  very  small  elUptical  pore. 

The  peristome  is  relatively  small,  subcircular  to  subpentagonal,  subcentral;  the  ambulacral 
furrows  simple  and  straight  for  a  short  distance  from  the  peristome,  then  forking  and  diverging 
nearly  symmetrically,  each  jjair  of  branches  proceeding  in  a  more  or  less  sinuous  course  and  with- 
out branching  for  over  half  the  way  to  the  margiii,  then  brandling  considerably,  the  branches 
being  given  ofl^  on  the  inside  of  the  more  important  furrow,  which  continues  to  diverge  more  and 
more  as  the  margin  is  approached. 

The  periproct  is  both  relatively  and  actually  very  small,  subcircular,  inframarginal,  a  short 
distance  in  from  the  point  of  the  lai"ge,  central  notch  in  the  posterior  border. 

Related  fonns. — This  species  is  not  closely  allied  to  any  other  American  form.  It  bears  a 
superficial  resemblance  to  Periarchus  lyelli  and  P.  alius  but  is  readily  separated  from  each  of 
them  by  the  character  of  its  ambulacral  furrows,  its  inframarginal  periproct,  and  the  large 
projections  and  notches  in  its  posterior  margin.  It  is  similar  in  general  features  to  two  foreign 
forms — S.  subrotunda  Lamarck,'  from  the  lower  Miocene  of  Bordeaux,  France,  and  S.  tarra- 
conensis  Lambert,  from  the  Burdigalien  Miocene  of  Barcelona,  Spain.  From  each,  however,  it 
can  be  easily  distinguished  by  its  much  more  pronounced  posterior  notches  and  projections  and 
by  its  less  central  apex. 

Localities. — Jones  Wharf,  St.  Marys  County,  (figured  specimen),  Governor  Run,  C'alvert 
County,  and  Dover  Bridge,  Dorchester  County,  Md. 

1  Agassiz's  monograph  Des  scutelles,  pp.  7&-78,  PI.  XVII,  figs.  1-9.    Desor,  in  Synopsis  des  ^ckinides,  p.  232,  says  that  *S.  siibrotunda  Lamarctt 
is  from  the  lower  Miocene. 


MIOCENE    ECHINODEEMATA.  189 

Geologic  horizon. — Choptank  formation,  middle  Miocene. 

Collections. — Maryland  Geological  Survey;  Johns  Hopkins  University;  U.  S.  National 
Museum;  Academy  of  Natural  .Sciences  of  Philadelphia. 

ScxrTELLA  GABBi   (Remond)  Merriam. 
Plate  LXXXVIII,  figure  la-b. 

IClypeaslcT  gabbi  Remond,  3S63,  Califciniia  Acad.  Sci.  Proc,  Vol.  3,  pp.  53,  54,  no  figure.     See  description  on  page  211 

of  the  present  work. 
IClypeaster  gabbi'Meek,  1864,  Smitlisoiiian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

IClypeaster  gabbi  Gabb,  1869,  Geol.  Survey  California,  Paleontology,  vol.  2,  pp.  36,  109,  PI.  XII,  figs.  04,  64a. 
ICly-peaster  gabbi  Cooper,  1888,  Cat.  California  fossils:  State  Mineralogist  Seventh  Rept.,  p.  271. 

Scutella  gabbi  Merriam,  1899,  California  Acad.  Sci.  Proc,  3d  ser.,  Geologj',  vol.  1,  No.  5,  p.  168,  PL  XXII,  figs.  5,  5a. 
Echinarachnius  gabbi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  703. 

Description. — The  writer  has  been  unable  to  obtain  any  specimens  '  of  this  form.  The 
description  of  Merriam  will  therefore  be  repeated  verbatim : 

Test  circular,  much  depressed,  margin  thin.  Average  specimens  25  to  30  mm.  in  diameter,  largest  specimens 
ranging  up  to  40  and  45  mm.  in  diameter. 

Petals  short,  not  extending  more  than  two-third.s  of  the  distance  to  the  margin;  excepting  the  anterior  one,  they  are 
nearly  closed  at  the  ends.  Anterior  petal  wide  open.  Except  in  the  anterior  area  the  ambulacral  plates  suddenly 
enlarge  and  the  area  rapidly  widens  beyond  the  ends  of  the  petals.  In  these  areas,  pairs  of  small,  round  pores,  diverging 
strongly  from  the  ends  of  the  petals,  may  be  present  almost  to  the  margins.  In  the  anterior  petal  the  plates  do  not 
enlarge  as  noticeably  toward  the  margin  as  in  the  others,  neither  do  the  more  persistent  j)ore  pairs  diverge  as  much. 

Apical  sliield  with  four  genital  pores,  there  being  none  at  the  end  of  the  posterior  interambulacral  area.  Anus 
marginal  to  supramarginal ;  in  quite  a  number  of  specimens  it  is  found  to  be  entirely  on  the  upjier  surface.  No  marked 
difference  is  noticeable  between  the  tubercles  of  the  upper  and  lower  surfaces. 

The  ambulacral  furrows  of  the  actinal  surface  are  not  usually  well  preserved  and  have  been  clearly  seen  on  only  a 
few  specimens;  they  divide  dichotomously  a  little  less  than  half  way  to  the  margin. 

Related  forms. — The  form  described  and  figured  by  Merriam  differs  in  several  respects  from 
that  originally  described  by  Remond.  Remond's  was  subelevated,  comparatively  thick  and 
with  margin  rounded.  Merriam's  is  much  depressed,  and  with  margin  thin.  The  petals  of 
Remond's  form  were  elongated  and  open  at  their  extremities — those  of  Merriam  are  short  and, 
excepting  the  anterior  one,  are  nearly  closed  at  the  ends.  In  Remond's  form  the  ambulacral 
furrows  are  straight,  which  led  to  his  placing  the  form  in  the  genus  Cl3^easter;  in  Merriam's 
the  furrows  divide  dichotomously  a  little  less  than  half  way  to  the  margin,  which  indicates  a 
Scutella.  These  differences  are  too  important  to  be  ignored  and  raise  the  cjuestion  whether 
Merriam  has  described  and  figured  identically  the  same  form  as  Remond.  The  location  of 
Remond's  type  is  imknown  and  he  failed  to  give  any  figures ;  but  his  other  work  is  of  too  high  an 
order  to  justify  any  radical  departure  from  his  description,  and  his  form  is  therefore  placed  in  the 
synonomy  of  the  present  species  with  an  interrogation  mark  as  indicative  of  the  doubt  that 
exists  in  regard  to  the  matter.  It  is  not  at  all  improbable  that  the  investigator  who  obtains  con- 
siderable material  from  Remond's  locality,  San  Pablo  Bay,  south  of  Mare  Island,  Cal.,  may  dis- 
cover a  form  more  nearly  corresponding  to  Remond's  description  than  the  one  here  described. 

Merriam's  Scutella  gahhi  is  most  closely  related  to  S.  fairhanlsi,  which,  however,  differs, 
according  to  Pack,  in ' '  attaining  a  greater  size,  in  having  a  slightly  imdiilating  marginal  outline, 
in  having  deeper  and  better  marked  furrows  on  the  actinal  surface,  and  in  having  the  anal  pore 
entirely  upon  the  upper  surface." 

Localities. — San  Pablo  Bay  (Remond,  Gabb,  Merriam,  Weaver) ;  Walnut  Creek  (Gabb, 
Weaver) ;  and  Martinez  (Gabb) ,  Cal. 

Geologic  horizon. — San  Pablo  formation,  upper  Miocene.  Merriam  states  that  it  occurs  in 
the  lowest  beds  of  the  San  Pablo  formation. 

Collection. — University  of  California  (19425). 

1 

1  Since  this  description  was  written  the  specimen  figured  was  lent  to  the  writer  by  Merriam.  A  study  of  thL;  specimen  strengthens  the  writer's 
doubt  as  to  its  being  the  same  form  as  that  described  by  Remond.  It  has  also  made  him  inclined  to  regard  Merriam's  S.  gabbi  as  very  probably 
the  same  as  S.fairbanksi  Pack. 

39S00°— 15— 13 


190  MESOZOIC   AND    CENOZOIC   ECHINODEKMATA    OF    THE    UNITED    STATES. 

Genus  DENDRASTEB  Agassiz  emend. 

Deudraster  L.  Agassiz,  1847,  Cat.  raisonn^  ^chinodermes;  Soc.  Nat.  Ann.,  vol.  7,  p.  135. 

Echinarachnius.  A.  Agassiz,  1872  (subgenus)  pars,  Revision  of  the  Ecliini,  Mus.  Comp.  Zoology  IIlus.  Gat.  7,  pp.  107,  524, 
Echinarachnius  Duncan,  1801  (subgenus)  pars.  Revision  genera  and  great  groups  Echinoidea,  p.  158. 
Echinarachnius  Grabau  and  Shimer,  1910,  North  American  index  fossils,  p.  592. 

The  genus  Dendraster  as  used  here  is  that  of  Agassiz  with  a  slight  amendment  enlarging  it. 
It  is  here  regarded  as  including  the  Scutella-like  forms  having  a  decidedly  posteriorly  excentric 
apical  system,  very  unequal  petals,  ambulacra!  furrows  bifurcating  near  the  peristome,  and  the 
periproct  inframarginal,  marginal,  or  supramarginal.  The  species  D.  excentricus  is  the  type  of 
the  genus. 

Some  confusion  exists  in  regard  to  the  forms  included  in  the  present  genus  by  reason  of  the 
use  of  the  generic  term  Echmarachnius  by  some  authors  as  a  subgenus  of  ScuteUa  for  the  forms 
having  an  excentric  apical  system.  Duncan  is  partly  responsible  for  this,  having  proposed  it 
in  his  revision  of  the  Echinoidea.  In  Eastman's  translation  of  Zittel's  Paleontology  the  sug- 
gestion of  Duncan  was  carried  out,  and  in  Grabau  and  Shimer 's  "Index  fossils  of  North 
America"  more  positive  action  was  taken  by  divorcing  Echinarachnius  from  Scutella  and  still 
ascribmg  it,  and  basing  it  essentially  upon,  the  excentric  apical  system. 

The  genus  Echinarachnius  was  established  by  Leske  in  1778,  what  is  evidently  his  type 
species  being  Echimis  flacenta  Linne.  Neither  this  species  nor  any  of  the  aUied  forms  he 
incidentally  mentioned  had  an  excentric  apical  system.  The  species  'placenta  is  now  recognized 
(though  with  doubtful  propriety)  as  the  type  of  the  genus  Arachnoides  Klein.  (See  p.  124.) 
Gray,  in  1825,  redrew  and  enlarged  Echinarachnius  Leske,  retaining  placenta  as  the  type  species 
and  adding  ScuteUa  parma  Lamarck  and  ScuteUa  lenticularis  Lamarck,  neither  of  which  has  an 
excentric  apical  system.  A.  Agassiz,  in  1872,  reduced  Echinarachnius  to  the  rank  of  a  sub- 
genus under  Scutella;  distmguishing  it  chiefly  by  having  "interior  pillars  more  or  less  coiicentric 
with  the  edge,"  and  inclucUng  both  forms  with  central  apical  system,  E.  parma,  and  excentric 
apical  system,  E.  excentricus.  In  view  of  these  facts  it  is  difficult  to  see  any  grounds  for  the 
use  of  the  name  Ecliinarachnius  for  forms  with  an  excentric  apical  system. 

As  a  result  of  the  discovery  in  California  deposits  of  many  specimens,  including  several 
new  species,  having  an  excentric  apical  system,  the  writer  has  been  led  to  differ  with  A.  Agassiz 
and  regards  the  excentricity  of  the  apical  system  as  a  fundamental  and  satisfactory  basis  of 
separation  and  thei'efore  regards  the  genus  Dendraster  L.  Agassiz  as  well  founded.  Stefanani^ 
appears  to  have  come  to  the  same  conclusion. 

Dendraster  perrini  (Weaver). 
Plate  LXXXVIII,  figures  2,  3a-c. 

Scutella  perrini  Weaver,  1908,  California  ITniv.  Dept.  Geology  Bull.,  vol.  5,  No.  17,  p.  273,  PI.  XII,  fig.  2. 
Astrodapsis  perrini  Rathbun,   1908,  U.  S.  Nat.  Mus.  Proc,  vol.  35,  -p.  342.    Listed  on  authority  of  R.   Arnold   and 

erroneously  ascribed  to  Merriam. 
Scutella  perrini  Arnold,  1909,  U.  S.  Geol.  Survey  Geol.  Atlas,  Santa  Cruz  folio  (No.  163),  p.  6. 
Scutella  perrini  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  396,  pp.  30,  34,  38,  162,  PI.  XXVIII,  flgs.  1,  2. 
Echinodiscus  (?)  perrini  Lambert,  1909,  Rev.  crit.  pal6ozoologie,  vol.  13,  p.  122. 
Scutella  perrini  Arnold  and  Anderson,  1910,  U.  S.  Geol.  Survey  Bull.  398,  p.  338,  PI.  L,  figs.  1,  2. 
Merriamaster  perrini  Lambert,  1911,  Rev.  crit.  paleozoologie,  vol.  15,  p.  64. 
Merriamaster  perrini  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  704. 

Determinative  characters. — Test  medium  in  size;  usually  circular  rarely  longitudinally  oval 
m  marginal  outHne,  broadest  centrally;  upper  surface  greatly  depressed,  slightly  convex,  rising 
gradually  from  the  unusually  tliick  margin  to  the  low  ajiex  which  is  slightly  excentric  anteriorl3'; 
under  surface  concave.  Tubercles  conspicuous,  nearly  equally  so  over  the  whole  test;  not 
close  together.  Apical  system  excentric  posteriorly,  fi'om  about  one-sixth  to  about  one-fifth 
the  radius  from  the  center.  Ambulacral  petals  large,  wide,  broadly  subelUptical,  all  of  them 
extending  nearly  to  the  margin,  wide  open  at  the  ends;  interporiferous  areas  very  wide,  some- 
times faintly  tumid,  the  posterior  paired  petals  shorter  than  the  others,  though  less  so  than  in 

1  Stetanani,  G.,  Soc.  geol.  italiana  Boll.,  vol.  33,  p.  704. 


MIOCENE   ECHINODEKMATA.  191 

allied  forms  and  less  divergent  than  the  anterior  pair.  Peristome  small,  slightly  excentrio 
posteriorly;  ambnlacral  furrows  straight  and  simple  for  a  short  distance  from  the  peristome, 
then  forking,  the  branches  diverging  and  extending  nearly  to  the  margin.  Periproct  very 
small,  circular,  inframarginal,  nearly  marginal. 

Dimensions. — Largest  specimen  studied:  Length  58  milUmeters;  width  58  milhmeters: 
height  10  milhmeters.  Specimen  A:  Length  46  millimeters;  width  43  milhmeters;  height 
9  milhmeters.    Specimen  B :  Length  45  milhmeters ;  width  4.3  milhmeters ;  height  9  milhmeters. 

Description. — The  test  of  this  recently  described  Cahfornian  species  is  medium  in  size, 
ranging  from  about  1^  to  nearly  2 J  inches  in  diameter.  In  marginal  outhne  it  is  usually  circular, 
though  sometimes  longitudinally  oval;  broadest  opposite  the  middle.  The  upper  surface  is 
greatly  depressed,  slightly  convex,  rising  gradually  from  the  margin  to  the  apex,  which  is  low,  and 
shghtly  excentric  anteriorly.  The  margin  is  unusually  tliick  for  a  scutellid  form  and  the  sub- 
marginal  area  beyond  the  ends  of  the  petals  is  very  narrow.  The  under  surface  is  concave;  the 
concavity  gradually  increasing  from  the  margm  to  the  peristome,  where  it  is  from  a  fourth  to 
a  third  of  the  height  of  the  test. 

The  ambulacral  areas  are  wide,  widest  at  the  margin  where  they  are  %vider  than  the  inter- 
ambulacral  areas;  dorsal  portions  petaloid.  The  petals  are  large,  the  total  area  covered  by 
them  being  greater  relatively  than  in  most  related  forms,  wide,  and  widening  rapidly  near  the 
apical  system;  broadly  subelhptical  in  outhne;  the  anterior  pair  longer  than  the  posterior  pair 
though  less  so  than  in  alhed  forms,  the  odd  petal  slightly  longer  than  the  anterior  pair,  all 
of  them  extending  nearly  to  the  margin  and  wide  open  at  the  ends;  the  posterior  pair  less 
divergent  than  the  anterior  pair.  The  poriferous  zones  are  of  moderate  mdth,  pores  oval; 
pairs  of  pores  conjugated.  The  interporiferous  areas  are  unusually  wide,  from  three  to  four 
times  as  wide  as  the  poriferous  zones  and  sometimes  faintly  tumid  on  unweathered  specimens. 

The  interambulacral  areas  are  rather  narrow  and  nearly  equal  in  width  between  the  petals, 
wide  at  the  margin.  The  whole  surface  of  the  test,  including  the  margin  and  the  interporiferous 
areas,  is  covered  with  perforate  tubercles  which  are  relatively  larger  and  more  conspicuous  than 
in  most  related  forms  and  which  project  above  the  edges  of  the  wide  scrobicules  in  wiiich  they 
are  placed.  The  tubercles  are  only  shghtly  larger  on  the  under  than  on  the  upper  surface  and 
they  are  not  very  close  together. 

The  apical  sj^stem  is  excentric  posteriorly,  though  less  so  than  in  most  related  forms,  being 
situated  from  about  one-sixth  to  about  one-fifth  the  distance  from  the  center  to  the  posterior 
margin.  There  is  a  large  subpentagonal  madreporite,  four  genital  pores  situated  at  the  points 
of  the  pentagon,  the  anterior  two  being  nearer  together  than  the  posterior  two,  and  five  small 
radial  plates  each  perforated  by  a  minute  jjore. 

The  peristome  is  small,  circular,  shghtly  excentric  posteriorly  just  beneath  the  apical 
system;  ambulacral  furrows  straight  and  simple  for  a  short  distance  from  the  peristome,  then 
forking,  the  branches  diverging  and  extending  almost  to  the  margin. 

The  periproct  is  very  small,  circular,  inframarginal,  nearly  marginal. 

Related  forms. — D.  perrini  is  closely  related  to  D.  arnoldi,  but  can  be  separated  from  it  by 
its  larger  petaloidal  area,  its  wider  and  less  tumid  interporiferous  areas,  its  broader  and  less 
gradually  ■widening  petals,  and  its  relatively  longer  posterior  petals. 

In  its  circular  form  and  its  thick  margin  D.  perrini  presents  an  interesting  resemblance  to 
Mortonella  quinquefaria,  but  is  easily  separated  by  its  posteriorly  excentric  apical  system,  its 
relatively  larger  petalloidal  area  and  narrower  submarginal  area,  and  by  the  inframarginal 
position  of  its  periproct. 

Lambert's  genus  Merriamaster  is  not  recognized,  as  it  is  based  on  the  erroneous  idea  that  the 
ambulacral  furrows  are  simple  as  in  Laganum. 

Locality. — Zapato  Creek,  one-half  mile  south  of  A.  Kreyenhagen's  place,  Conhnga  district, 
California. 

Geologic  horizon. — Etchegoin  formation  (apparently  limited  to  the  upper  portion),  upper 
Miocene  and  lower  Phocene  (?)• 

Collections. — U.  S.  National  Museum  (165560,  A,  B);  University  of  Cahfornia. 


192  MESOZOIC   AND   CENOZOIC    ECHISTODEKMATA    OF    THE    UNITED   STATES. 

Dendeaster  arnoldi  Twitche!^,  n.  sp. 
Plate  LXXXVIII,  figures  4a-d. 

Astrodapsis?  sp.  a  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  396,  p.  162,  PI.  XXVIII,  figs.  3,  3a. 
Astrodapsis?  sp.  a  Arnold,  1910,  U.  S.  Geol.  Survey  Bull.  398,  p.  338,  PI.  L,  figs.  3,  3a. 

^  Determinative  characters. — Test  small  to  medium  in  size;  subcircular  to  broadly  oval  in 
marginal  outline,  usuall}'  longitudinallj'  elongate,  more  rarely  transversely  elongate,  broadest 
centrally;  upper  surface  greatly  depressed,  sligbtly  convex,  rising  gradually  from  the  mod- 
erately thick  margin  to  the  low,  central  apex;  under  surface  concave.  Tubercles  crowded 
and  conspicuous,  notably  so  witliin  the  interporifei-ous  areas  and  between  the  ambulacral 
furrows.  Apical  sj'stem  excentric  jjosteriorlj-,  from  about  one-fifth  to  about  one-fourth 
the  radius  from  the  center.  Ambulacral  petals  of  medium  size,  extending  from  one-half  to 
two-tliirds  the  way  to  the  margin,  vade  open  at  the  ends,  moderately  wide;  interporiferous 
areas  notabl}-  tumid;  the  posterior  paired  petals  decidedly  shorter  than  the  rest  and  relatively 
shorter  than  in  closely  related  forms.  Peristome  small,  central  or  subcentral;  ambulacral 
furrows  straight  and  simjDle  for  a  short  distance  from  the  peristome,  then  forking,  the  branches 
diverging  and  extending  nearly  to  the  margui.  Periproct  veiy  small,  circular,  ioframarginal, 
nearly  marginal. 

;>>  Dimensions. — Type  specimen:  Lenglh  45  millimeters;  mdth  43  millimeters;  height  7 
millimeters.  Small,  transverselj-  elongate  specimen:  Length  22.5  millimeters;  width  24 
millimeters;  height  5  milUmeters. 

Description. — Tliis  species  is  found  in  association  with  D.  ferrini  and  D.  coalingaensis 
in  the  Etchegoin  formation  of  California.  It  is  rather  an  abundant  form.  A  number  of  specimens 
were  collected  b}-  Dr.  Ralph  Arnold,  of  the  United  States  Geological  Survey,  and  one  was 
figured  by  him.  The  species  is  therefore  named  in  liis  honor.  The  ^vl•iter  found  several  specimens 
among  the  material  studied  wliich  showed  bifurcating  ambulacral  furrows,  thus  proving  the  form 
to  be  alUed  to  Scutella,  instead  of  belonging  to  Astrodapsis,  the  genus  to  which  Arnold  doubtfully 
referred  the  form  he  figured.  The  test  of  tliis  species  is  small  to  medium  in  size,  ranging  from 
less  than  one-half  to  nearly  2  inches  in  diameter.  In  marginal  outhne  it  is  subcircular  to  broadly 
oval,  usually  longitudinally  elongate  more  rarely  transversely  elongate,  broadest  opposite  the 
middle  or  shghtl}-  to  the  rear  of  the  middle.  The  ujiper  surface  is  greatly  depressed,  shghtly 
convex,  rising  gradually'  from  the  margin  to  the  apex,  wliich  is  low  and  central  or  subcentral. 
The  margin  is  of  moderate  tliickness,  though  somewhat  variable,  sometimes  approaching  the 
tliickness  of  that  of  D.  perrini.  The  imder  surface  is  concave,  the  concavity  graduall}'  increasing 
from  the  margin  to  the  peristome. 

The  ambulacral  areas  are  wide,  widest  at  tlie  margin,  where  they  are  wider  than  the  inter- 
ambulacral  areas;  dorsal  portions  petaloid.  The  petals  are  of  medium  size,  moderately  wide 
and  tending  to  widen  gradually  to  near  their  distal  ends,  extending  from  one-half  to  two-thirds 
the  way  to  the  margin,  the  anterior  pair  decidedly  longer  than  the  posterior  pair,  the  odd  petal 
slightly  longer  than  the  anterior  pair;  more  subspatulate  than  subeUiptical  in  outhne;  wide  open 
at  the  ends.  The  poriferous  zones  are  wide,  pores  oval,  pairs  of  pores  conjugated.  The  inter- 
poriferous areas  are  rather  wide,  usually  from  two  to  three  times  the  width  of  the  poriferous 
zones,  and  notably  tumid. 

The  interambulacral  areas  are  rather  narrow  between  the  petals,  wide  at  the  margin.  The 
whole  surface  of  the  test  is  covered  with  tubercles  which  are  crowded  and  relatively  conspicuous, 
projecting  above  the  edges  of  the  rather  wide  scrobicules  and  being  especially  conspicuous  A^athin 
the  interporiferous  areas  and  between  the  ambulacral  furrows. 

The  apical  system  is  excentric  posteriorly,  situated  from  about  one-fifth  to  about  one- 
fourth  the  distance  from  the  center  to  the  posterior  margin.  The  madreporite  is  large  and  there 
are  four  genital  pores,  the  anterior  two  being  nearer  together  than  the  posterior  two,  and  five 
small  radial  plates  each  perforated  by  a  minute  pore. 

The  peristome  is  small,  subcircular,  central,  or  subcentral;  ambulacral  furrows  straight  and 
simple  for  a  short  distance  from  the  jjeristome,  then  forking,  the  branches  diverging  and  extend- 
ing nearly  to  the  margin. 


MIOCENE    ECHINODEKMATA.  193 

The  pei-iproct  is  very  small,  circular,  inframargiiial,  nearly  marginal. 

Related  forms. — D.  arnoldi  is  closely  related  to  D.  perrini,  but  can  be  separated  from  it  by 
its  smaller  petaloidal  area  and  broader  submarginal  area,  its  relatively  shorter  posterior  petals, 
its  narrower  interporiferous  areas,  and  its  narrower  and  less  rapidly  widening  petals.  D.  eirnoldi 
is  Uable  to  be  confused  with  D.  coalingaensis  at  times,  but  is  to  be  distinguished  from  the  latter 
by  its  thicker  margin,  less  symmetrically  elliptical  petals  wide  open  at  the  ends,  its  more  con- 
spicuous tubercles,  and  its  less  posteriorly  excentric  apex. 

Localities. — Near  A.  Kreyenhagen's  place  and  south  of  Lucile  Well,  2  miles  southwest  of 
Coalinga  in  Coahnga  district,  California. 

Geologic  horizon. — Etchegoin  formation,  upper  Miocene  and  lower  PHocene  (?). 

Collection. — U.  S.  National  Museum  (16.5707). 

Dendr.vster  gibbsii  (Remond). 
Plato  LXXXIX,  figs,  la-b,  2-4;  Plate  CVIII,  B. 

Scutella  gibbsii  Remond,  1863,  Califomia  Acad.  Sci.  Proc,  vol.  3,  pp.  13,  14. 

Scutella  gibbsii  Meek,  18G4,  Smithsonian  Misc.  Col.,  vol.  7  (183),  p.  2. 

Scutella  gibbsii  Gabb,  1SG9,  Geol.  Survey  Califomia,  Paleontology,  vol.  2,  pp.  37,  109,  PI.  Xlll,  figs.  66,  66a. 

Scutella  gibbsii  Cooper,  1888,  Cat.  California  fossils,  State  Mineralogist  Seventh  Kept.,  p.  271. 

Echinarachnius  gibbsii  Merriam,  1899,  California  Acad.  Sci.  Proc,  3d  ser.,  Geology,  vol.  1,  No.  5,  p.  169,  PL  XXII, 

fig.  7. 
fScutella  gibbsii  F.  Anderson,  190.5,  California  Acad.  Sci.  Proc,  3d  ser..  Geology,  vol.  2,  p.  180. 
Echinarachnius  ashleyi  (Merriam,  MS),  Arnold,  1907,  U.  S.  Geol.  Survey.  Bull.  322,  PI.  XXIV,  figs.  6,  7. 
1  Echinarachnius  excentricus  Eschscholtz  var.  Arnold  and  Anderson,  1907,  U.  S.  Geol.  Survey  Bull.  322,  PI.  XXIV, 

fig.  8.     This  is  apparently  a  somewhat  variant  form  of  Dendraster  gibbsii. 
Echinarachnius  gibbsii  Arnold,  1909  (pars),  U.  S.  Geol.  Survey  Bull   396,  pp.  24,  2.5,  27,  31,  34  (pars);  38,  42  (pars),  132, 

144,  146;  PI.  XIII,  figs.  1,  2;  PI.  XIX,  figs.  1,  2;  Pi.  XX,  fig.  7. 
non  Echinarachnius  gibbsii  Arnold,  1909,  (pars),  TJ.  S.  Geol.  Survey  Bull.  396,  pp.  34  (pars),  42  (pars),  162;  PI.  XXVIII, 

figs.  4,  4a. 
Echinarachnius  gibbsii  Arnold  and  R.  Anderson,  1910  (pars),  U.  S.  Geol.  Siirvey  Bull.  398,  pp.  316,  318;  PI.  XLI,  figs. 

1,  2;PI.  XLIl,  fig.  7. 
non  Echinarachnius  gibbsii  Arnold  and  R.  Anderson,  1910  (pars),  U.  S.  Geol.  Survey  Bull.  398,  p.  338;  PI.  L,  figs.  4,  4a, 
Dendraster  ashleyi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  706. 
Dendraster  gibbsii  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  704. 

Determinative  characters. — Test  small  to  large,  suboblong,  subquadrate,  suboval,  or  sub- 
ovate  in  marginal  outhne,  length  usually  equal  to  or  greater  than  width,  though  sometimes 
considerably  less,  usually  broadest  back  of  the  center;  upper  surface  convex,  much  depressed, 
though  less  so  posteriorly  than  anteriorly,  rising  directly  from  the  thin  margin  to  the  low, 
posteriorly  excentric  apex;  undersurface  flat.  Apical  system  very  exceiatric  posteriorly,  from 
one-third  to  more  than  one-half  the  radius  from  the  center.  Ambulacral  petals  large,  all  but 
the  odd  petal  approaching  rather  close  to  the  margin;  the  posterior  pair  shorter  than  the  others, 
more  divergent  than  the  anteriorly  curving  anterior  pair  and  with  widely  divergent  poriferous 
zones.  Peristome  small,  excentric  posteriorly,  though  less  so  than  apical  system;  ambulacral 
furrows  fork  near  the  peristome,  the  branches  at  first  diverging  then  converging  slightly  and 
proceeding  nearly  to  the  margin,  giving  off  only  a  few  branches.  Periproct  very  small,  cir- 
cular, inframarginal,  nearly  marginal. 

Dimensions. — Specimen  A  (PI.  LXXXIX,  figs,  la,  lb):  Length  62  millimeters;  width  59 
milhmeters;  height  13  miUimeters.  Specimen  B  (PI.  LXXXIX,  fig.  2):  Length  87  millimeters; 
width  81  miUimeters;  height  11  mUlimeters.  Specimen  C  (PI.  LXXXIX,  fig.  3):  Length  81 
miUimeters;  width  95  miUimeters;  height  16  miUimeters.  Specimen  D  (PI.  LJOCXIX,  fig.  4): 
Length  32  miUimeters;  width  33  miUimeters;  height  7  miUimeters. 

Description. — A  very  good  description  of  this  mteresting  Calif ornian  species  was  given  as 
early  as  1S63  by  Remond.  It  was  first  figured  by  Gabb  in  1869.  The  test  is  variable  in  size, 
ranging  from  about  1  to  3J  inches  in  diameter  and  from  one-eighth  to  one-half  inch  in  height. 
In  marginal  outline  it  varies  considerably,  being  usuaUy  suboblong  or  subc^uadrate;  sometimes 


194  MESOZOIC   AND   CENOZOIC    ECHINODERMATA    OF    THE    UNITED    STATES. 

suboval  or  subovate;  length  usually  equal  to  or  greater  than  width,  though  sometimes  con- 
siderably less,  usually  broadest  back  of  the  center  but  in  front  of  the  apical  system.  The  upper 
surface  is  somewhat  irregularly  convex;  much  depressed  though  less  so  posteriorly  than  ante- 
riorly, rising  directly  from  the  margin  to  the  low  apex  which  is  more  or  less  posteriorly  excen- 
tric,  sloping  more  steeply  posteriorly  than  anteriorly.  The  margm  is  thin  and  is  usually  shghtly 
notched  in  the  middle  of  the  posterior  end.     The  imder  surface  is  flat  or  shghtly  concave. 

The  ambulacral  areas  are  wide,  widest  at  the  margin,  where  they  are  wider  than  the  inter- 
ambulacral  areas;  dorsal  portions  petaloid.  The  petals  are  large,  the  total  area  covered  by 
them  being  greater  relatively  than  in  most  related  forms;  the  anterior  three  longer  than  the  pos- 
terior two,  the  odd  petal  equal  to  or  shghtly  longer  than  the  anterior  pair;  aU  of  them  except 
the  odd  petal  approaching  rather  close  to  the  margin.  The  anterior  paired  petals  curve  toward 
each  other,  so  as  to  be  less  divergent  than  the  posterior  pair,  which  are  very  short,  widely 
divergent,  and  have  their  anterior  side  the  longer  and  their  poriferous  zones  widely  divergent. 
The  poriferous  zones  are  of  moderate  width,  those  of  the  odd  petal  usually  being  narrower  than 
the  rest;  pores  oval  and  conjugated.  The  interporiferous  areas  are  wide,  much  wider  than  the 
poriferous  zones. 

The  interambulacral  areas  are  very  narrow  between  the  petals,  wide  at  the  margin.  The 
surface  of  the  test  is  covered  with  small  uniform  perforate  tubercles  which  are  slightly  larger 
on  the  under  surface. 

The  apical  system  is  very  excentric  posteriorly,  being  situated  from  one-third  to  more 
than  one-half  the  distance  from  the  center  to  the  posterior  margin.  The  specimens  which 
are  larger  and  more  elongate  longitudinally  are  those  with  the  most  excentric  apical  system. 
The  madreporite  is  large,  subpentagonal,  with  four  genital  pores  as  the  anterior  points  of  the 
pentagon,  the  two  anterior  nearer  together  than  the  two  posterior.  There  are  also  five  very 
small  I'adial  plates  each  perforated  by  a  minute  pore. 

The  peristome  is  small,  excentric  posteriorly,  though  decidedly  less  so  thaa  the  apical  system. 
The  ambulacral  furrows  are  simple  and  straight  for  a  short  distance  from  the  peristome, 
then  fork  nearly  symmetrically  into  two  strong  furrows  which  diverge  for  a  short  distance, 
then  converge  slightly  and  continue  nearly  to  the  margin.  In  yoimg  specimens  they  diverge 
continuously  to  the  margin.  There  do  not  appear  to  be  many  branches  given  off,  though  the 
specimens  are  rarely  sufficiently  well  preserved  to  show  this  feature. 

The  periproct  is  very  small,  circular  or  subcircular,  inframarginal,  nearly  marginal,  usually 
1  or  2  milhmeters  from  the  inner  edge  of  the  shght  notch  in  the  posterior  border. 

Belated  forms. — Dendraster  giihsii  is  most  closely  related  to  D.  exceniricus,  but  differs 
from  the  latter  in  having  its  apex  less  central,  its  apical  system  more  excentric,  its  posterior  petals 
less  widely  divergent  and  with  less  widely  divergent  poriferous  zones,  and  its  periproct  usually 
somewhat  nearer  to  the  border.  Some  of  the  younger  specimens  of  D.  gibhsii  also  resemble 
D.  coalingaensis,  but  can  be  separated  from  it  by  its  more  excentric  apical  system,  its  less  sym- 
metrically ehiptical  ambulacral  petals,  and  its  more  divergent  posterior  petals.  No  foreign 
forms  appear  to  be  closely  related  to  D.  gibhsii.  The  Patagonian  species  Scutella  patagonensis 
Desor  '  resembles  D.  gibhsii  in  occurrence  in  two  quite  different  forms,  one  longitudmally 
elongate  and  one  transversely  elongate,  which  yet  evidently  belong  to  the  same  species,  for 
they  grade  into  one  another  and  they  occur  together. 

Localities. — Kern  Lake,  Buena  Vista  County  (Remond);  near  Buena  Vista  Lake,  Kem 
County  (Gabb,  Merriam);  near  Santa  Cruz  (Ashley);  8  miles  north  of  Coahnga  (PL  LXXXIX, 
figs,  la,  lb) ;  ridge  south  of  Garcas  County,  Coahnga  district  (PI.  LXXXIX,  figs.  2,  3) ;  10  to  12 
miles  southeast  of  northwest  end  of  Kettleman  Hills,  Coahnga  district  (PI.  LXXXIX,  fig.  4); 
numerous  other  locahties  m  Coahnga  district  (includmg  U.  S.  Geol.  Survey  locahties  Nos.  3849, 
4751,  4753,  4755,  4757,  4767,  4768,  and  4806);  San  Jacmto;  Capitola  (Pack);  San  Gregorio 
(Pack) ;  Graciosa  Ridge  near  Orcutt,  Santa  Maria  district,  California.     

1  See  Reports  of  the  Princeton  University  expeditions  to  Patagonia,  1S95-1899,  vol.  4,  pt.  2,  pp.  55-60;  PI.  XI,  figs.  4a,  b,  c,  d,  e. 


MIOCENE   ECHINODEEMATA.  195 

Geologic  horizon. — .Jacalitos  and  Etchegoin  formations,  in  Coalinga  district,  upper  Miocene 
and  lower  Pliocene  (?).  Fernando  formation  in  Santa  Maria  district,  upper  Miocene  or  lower 
Pliocene. 

Collections.— U.  S.  National  Museum  (165547,  A;  165G11,  B,  C;  165704,  D);  University 
of  California,  California  Academy  of  Sciences;  Yale  University. 

Dendraster  oregonensis  (Clark). 

Plate  XC,  figure  1. 

Scuiella  (Echinarachnius)  oregonensis  Clark,  1909,  in  Dall,  U.  S.  Geol.  Survey  Prof.  Paper  59,  p.  140,  PI.  VII,  fig.  2. 

Determinative  cJiaracters. — Test  small;  subcircular  in  marginal  outline,  broader  posteriorly 
than  anteriorly;  the  whole  form  greatly  depressed,  the  upper  surface  moderately  convex, 
rising  directly  from  the  rather  thin  margin  to  the  low,  anteriorly  excentric  apex;  under  surface 
flat.  Apical  system  excentric  posteriorly,  about  one-fourth  the  radius  from  the  center.  Ambu- 
lacral  petals  relatively  large,  approaching  rather  close  to  the  margin;  the  two  posterior  shorter 
than  the  anterior  three  and  with  posterior  poriferous  zones  straight  or  nearly  so;  open  at  their 
ends.  Peristome  circular,  subcentral.  Ambulacral  furrows  feeble.  Periproct  small,  sub- 
circular,  supramarginal. 

Dimensions. — Length  20  miUimeters;  width  20  millimeters;  height  3  milUmeters. 

Description. — This  recently  described  Pacific  coast  Dendraster  is  one  of  the  smallest 
representatives  of  the  genus,  rarely  exceeding  an  inch  in  diameter. 

In  marginal  outUne  it  is  subcircular;  though  broader  posteriorly  than  anteriorly.  The 
whole  form  is  greatly  depressed,  the  upper  surface  being  evenly  rounded  and  rising  directly 
from  the  rather  thin  margin  to  the  low  apex  which  is  situated  foi-ward  of  the  center.  The 
under  surface  is  flat  or  faintly  concave. 

The  ambulacral  areas  are  rather  iiarrow;  dorsal  jjortions  petaloid.  The  petals  are  rela- 
tively large,  approaching  rather  close  to  the  margin,  the  two  posterior  shorter  than  the  anterior 
three,  of  which  the  odd  petal  is  the  longest.  The  petals  are  straight  or  nearly  so,  the  anterior 
pair  sUghtly  more  divergent  than  the  posterior  pair,  and  all  are  ojjen  at  their  ends.  The 
poriferous  zones  are  broad,  jjores  oval,  pairs  of  pores  conjugated;  the  posterior  zones  of  both 
pairs  straight  or  nearly  so.  The  interporiferous  areas  are  narrow,  about  as  wide  or  sHghtly 
wider  than  the  poriferous  zones. 

The  interambulacral  areas  are  broad,  about  equally  so  between  the  petals.  The  surface 
of  the  test  is  closely  set  with  small  tubercles,  apparently  imperforate,  set  in  deei)  scrobicules, 
the  tubercles  being  slightly  larger  on  the  under  surface. 

The  apical  system  is  excentric  posteriorly,  being  situated  about  one-fourth  the  distance 
from  the  center  to  the  posterior  border.  The  details  could  not  be  made  out  upon  the  specimens 
studied. 

The  peristome  is  small,  circular,  subcentral;  the  ambulacral  furrows  feeble,  not  showing 
very  well  upon  the  s^^ecimens;  but  apparently  sim2:)le  and  straight  for  a  short  distance  from 
the  peristome,  then  forking  symmetrically. 

The  periproct  is  small,  subcircular,  supramarginal,  about  1  millimeter  from  the  posterior 
ends. 

Related  forms. — D.  oregonensis  is  closely  allied  to  D.  interllneaius ,  the  superficial  resemblance 
being  very  striking,  but  differs  in  having  all  the  petals  open  at  the  ends  and  the  posterior  and 
anterior  paired  petals  less  symmetrically  subeUiptical  in  form  by  reason  of  the  fact  that  the 
posterior  poriferous  zones  are  straight  or  nearly  so.  D.  oregonensis  also  differs  m  being  relatively 
higher  in  proportion  to  its  width  and  has  a  relatively  larger  periproct.  These  differences  are 
not  very  pronounced,  and  further  collecting  may  result  in  the  merging  of  the  two  species. 

Localities. — Near  Empire  City  and  Fossil  Point,  Coos  Bay,  Oreg. 

Geologic  horizon. — Empire  formation,  upper  Miocene. 

Collection. — U.  S.  National  Museum  (15.3975). 


196  MESOZOIC    AND    CE^^OZOIC    ECHINODERMATA    OF    THE    UNITED    STATES. 

Dendeaster  coauxgaexsis  Twitchell,  n.  sp 
Plate  XC,  figures  2a-c. 

Echinarachnius  gibbsii  Arnold,  1909,  pars,  V.  S.  Geol.  Survey  Bull.  39G,  pp.  34  pars,  42  pars,  162;  PL  XXVIII,  fio^. 

4,  4a. 
Echinarachnius  gibbsii  Arnold,  1910,  pars,  U.  S.  Geol.  Survey  Bull.  39S,  p.  338,  PI.  V,  figs.  4,  4a. 

Determinative  charaeters. — Test  small;  broadly  ovate  in  marginal  outline;  broadest  about 
opposite  or  to  the  rear  of  the  apical  system;  upper  surface  convex,  greatly  depressed  though 
less  so  posteriori}^  than  anteriorly,  arising  directty  from  the  thin  margin  to  the  apex  which  is 
excentric  posteriorly  and  about  coincident  with  the  apical  s3-stem;  under  surface  concave 
around  the  peristome.  Apical  system  excentric  posteriorly,  about  one-fourth  the  radius  from 
the  center.  Ambulacral  petals  vnde,  straight  and  symmetricallj'  subellipical;  the  posterior 
pair  shorter  than  the  others,  and  usually  less  divergent  than  the  anterior  pair.  Peristome 
small,  shghtly  excentric  posteriorly;  ambulacral  furrows  simple  and  straight  for  about  one- 
third  the  radius,  then  forking,  each  jvair  of  branches  diverging  continuously  nearly  to  the  margin, 
where  they  spht  into  several  small  branches.  Periproct  small,  circular,  inframarginal,  almost 
marginal. 

Dimensions. — Length  .3.3  milhmeters;  width  31  millimeters;  height  5  milHmeters.  One  of 
the  smallest  specimens  studied  was  only  14  millimeters  in  diameter. 

Description.- — This  small  Dendraster  is  found  in  association  with  D.  perrini  in  the  CoaUnga 
district,  Cahfornia,  whence  the  name  given.  A  number  of  specimens  were  collected  and  one 
was  figured  by  Ai-nold.  The  test  is  small,  ranging  from  one-half  to  IJ  inches  in  diameter; 
broadly  ovate  in  mai^inal  outUne,  broadest  opposite  or  sUghtly  to  the  rear  of  the  apical  system. 
The  upper  surface  is  somewhat  irregularly  convex,  greatly  depressed,  though  less  so  posteriorly 
than  anteriorly,  rising  directly  from  the  margin  to  the  low,  posteriorly  excentric  apex.  The 
mai^n  is  thin. 

The  ambulacral  areas  are  ^\^de,  widest  at  the  margin,  where  they  exceed  the  interambu- 
lacral  areas  in  width;  dorsal  portions  petaloid.  The  petals  are  of  medium  length,  wide,  straight, 
and  symmetrically  subelhptical,  svide  open  at  the  ends;  the  anterior  three  longer  than  the  pos- 
terior two,  the  odd  petal  sHghtly  longer  than  the  anterior  pair;  the  posterior  pair  usually  less 
divergent,  sometimes  about  as  equally  divergent  as  the  anterior  pair.  The  poriferous  zones 
are  wide,  outer  row  of  pores  subeUiptical,  inner  row  subcircular;  pairs  of  pores  conjugated.  The 
interporiferous  areas  are  \\'ide,  and  sUghtly  tumid. 

The  interambulacral  areas  are  narrow  between  the  inner  ends  of  the  petals,  wide  from  the 
outer  ends  of  the  petals  to  the  margin,  each  area  of  about  equal  width  ^^^th  the  others.  The 
sm-face  of  the  test  is  covered  with  small,  uniform,  perforate  tubercles  in  deep  scrobicules.  The 
tubercles  and  scrobicules  are  sUghtly  larger  on  the  under  surface  and  larger  than  in  related 
forms. 

The  apical  system  is  excentric  posteriorly,  being  situated  about  one-fourth  the  distance 
from  the  center  to  the  jiosterior  border  and  coincident  or  very  nearly  coincident  mth  the  apex. 
There  is  a  large  pentagonal  madreporite,  four  genital  pores  of  which  the  anterior  pair  are  nearer 
together  than  the  posterior  pair;  and  five  small  radial  plates  each  perforated  by  a  minute  pore. 

The  peristome  is  small,  subcircular,  sUghtly  excentric  posteriorly,  but  sUghtly  less  so  than 
the  apical  system.  The  ambulacral  furrows  are  simple  and  straight  for  about  one-third  the 
way  to  the  margin,  then  fork  symmetrically,  each  pair  of  branches  diverging  continuously  to 
near  the  margin  where  thej'  spUt  into  several  small  branches. 

The  periproct  is  small,  circular,  inframarginal,  almost  marginal,  usuaUy  less  than  a  milli- 
meter from  the  posterior  edge. 

Belated  forms. — D.  coalingaensis  is  closely  related  to  D.  excentricus,  of  which  it  may  be  an 
ancestral  form.  It  differs  from  the  latter,  however,  in  being  much  smaller  and  less  tumid 
centrally,  in  ha\'ing  its  apex  less  central  and  more  nearly  coincident  with  the  apical  system, 
and  in  having  its  periproct  nearer  to  the  margin.  D.  coalingaensis  also  closely  resembles  D. 
gibbsii,  especially  the  young  specimens  of  the  latter  species,  but  can  be  readily  separated  by  its 


MIOCENE    ECHINODERMATA.  197 

much  less  excentric  apical  system,  its  more  symmetrically  elliptical  ambulacral  petals,  and  the 
fact  that  its  posterior  petals  diverge  less  wddely  and  also  have  poriferous  zones  which  are  less 
widely  divergent  at  their  ends  and  more  equal  in  length.  Some  specimens  of  D.  arnoldi  resemble 
D.  coalingaensis;  but  they  have  tliicker  margins,  more  widely  open  ambulacral  petals,  more  con- 
spicuous tubercles,  more  tumid  interporiferous  areas,  and  a  central  apex  wliich  is  also  not  coin- 
cident -with  the  apical  system. 

Localities. — Near  A.  Kreyenhagen's  place  (type),  and  1,244-foot  liill  4  miles  southeast  of 
northwest  end  of  Kettleman  Hills,  in  CoaUnga  district,  Cahfornia. 

Geologic  horizon. — Etchegoin  formation  (apparently  Umited  to  the  upper  jjortion  of  the 
formation),  upper  Miocene  and  lower  Phocene  ( ?). 

Collection. —V.  S.  National  Museum  (165.537). 

Dendeaster  sp.  (Conrad). 

Scutella  sp.  Conrad,  1857,  U.  S.  Pacific  R.  R.  ExpL,  vol.  7,  PI.  X,  figs.  3,  4;  no  description. 
Dendraster  sp.  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  704. 

As  Conrad  gave  no  description  of  this  form  its  exact  relationships  can  not  be  determined 
with  certainty.  It  resembles  Dendraster  interlineatus  in  some  respects,  but  not  closely  enouo-h 
to  justify  its  identification  with  that  species. 

EcHiNARACHNius  sp.  Conrad. 

Echinarachnius  sp.  Conrad,  1857,  U.  S.  Pacific  R.  R.  ExpL,  vol.  7,  PL  IX,  fig.  5;  no  description. 

This  is  only  a  poor  figure  of  an  imperfect  specimen,  unaccompanied  by  a  description.  It 
is  not  entitled  to  recognition  and  the  exact  relationships  can  not  be  determined  from  such  data. 

Genus  ASTBODAPSIS  Conrad  (amended). 

Astrodapsis  Conrad,  1869,  Acad.  Nat.  Sci.  Philadelphia  Proc,  voL  8,  p.  315. 
Astrodapsis  Conrad,  1857,  U.  S.  Pacific  R.  R.  ExpL,  vol.  7,  Pal.  Rept.,  p.  196. 
Astrodapsis  R^mond,  1863,  California  Acad.  Nat.  Sci.  Proc,  vol.  3,  p.  52. 

The  wi-iter  does  not  agree  with  Duncan  ^  in  regai'ding  Conrad's  genus  Astrodapsis  as  a 
synonym  of  Brey:iius's  genus  Arachnoides.  The  inframarginal  position  of  the  i^eriproct, 
the  depressed  apical  system,  and  the  elevated  ambulacral  areas  alternating  with  depressed 
interambulacral  areas  sufficiently  distinguish  Astrodapsis  from  Arachnoides. 

Conrad's  description  of  his  genus  is  as  follows:  "Suboval;  depressed;  ambulacral  areas 
elevated  or  ridged;  ambulacra  nearty  straight,  widely  open  at  the  extremity;  mouth  central; 
anus  submarginal,  beneath;  radiating  grooves  as  in  Laganum."  This  description  was  good 
in  view  of  the  small  amoimt  of  material  Conrad  had,  but  it  now  becomes  necessary  to  redraw 
tlie  diagnosis  of  the  genus  in  order  to  make  a  few  emendations. 

Description. — Test  depressed,  subdiscoidal  to  broadly  subconical  in  general  form,  circular 
to  subelHptical  in  marginal  outhne,  margin  varying  from  thin  to  very  thick,  with  or  without 
notches  opposite  the  ambulacral  petals.  Ambulacral  areas  elevated  or  ridged;  interambula- 
cral areas  depressed.  Ambulacral  petals  straight,  extending  nearly  to  the  margin,  widely  open 
at  the  ends ;  poriferous  zones  nearly  parallel,  continuously  diverging,  or  diverging,  converging, 
and  again  diverging.  Apical  system  more  or  less  depressed.  Peristome  central  or  subcentral. 
Main  ambulacral  grooves  simple  and  straight  from  peristome  to  margin,  continuing  as  fainter 
gi-ooves  or  processes  over  the  margin  and  along  the  middle  of  the  ambulacral  ridges  nearly  to 
the  apical  system;  two  faint  lines  or  processes  are  given  off  from  the  main  grooves  from  one- 
half  to  two-thirds  the  way  to  the  margin,  which  continue  over  the  margin  and  along  the  upper 
surface  between  the  tops  of  the  ambulacral  ridges  and  the  bottoms  of  the  ambulacral  depres- 
sions nearly  to  the  apical  system.     Periproct  small,  inframarginal,  almost  marginal. 

1  Duncan,  P.  M.,  Revision  of  genera  and  great  groups  of  the  Echinoidea;  Linn.  Soc.  Jour.  Zoology,  vol.  23,  p.  165, 1891. 


198  MESOZOIC   AND    CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

AsTRODAPSis  ANTisELLi  Conrad. 

Plate  XCIV,  figures  3,  4a-b. 

Astrodapsis  antiselli  Conrad,  1856,  Acad.  Kat.  Sci.  Philadelphia  Proc,  vol.  8,  p.  315;  no  figures. 

Astrodapsis  antiselli  Conrad,  1857,  U.  S.  Pacific  R.  R.  ExpL,  vol.  7,  p.  196,  PI.  X.  figs.  1,  2. 

Astrodapsis  antiselli  Meek.  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183).  p.  2. 

Astrodapsis  antiselli  Gabb,  1869,  California  Geol.  Survey  Rept.,  Paleontology,  vol.  2.  p.  110. 

Astrodapsis  antiselli  Cooper,  1888,  State  Mineralogist  California  Seventh  Rept..  p.  270. 

Astrodapsis  antiselli  Arnold,  1908,  U.  S.  Nat.  Mus.  Proc,  vol.  34,  PI.  XXXV,  fig.  10;  no  description. 

Astrodapsis  antiselli  Arnold,  1909,  U.  S.  Geol.  Survey  Geol.  Atlas,  Santa  Cruz  folio  (No.  163),  PI.  II,  fig.  58. 

non  Astrodapsis  antiselli  var.  amoldi  Pack.  1909,  Univ.  California  Dept.  Cxeology  Bull.,  vol.  5,  No.  18,  pp.  279-281,  PI. 

XXIV,  figs.  1,  2.    See  Astrodapsis  amoldi. 
Astrodapsis  antiselli  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  702. 

Determinative  characters. — Test  medium  in  size;  regularly  oval  in  marginal  outline,  longer 
than  broad,  slightly  truncated  at  anterior  end,  slightly  pointed  at  posterior  end,  with  faint 
notches  opposite  ends  of  petals;  margin  roimded  and  very  thick,  ahnost  as  thick  as  rest  of 
test.  The  whole  form  is  considerably  depressed,  almost  equally  so  from  edge  to  edge,  and 
therefore  subdiscoidal;  the  upper  surface  with  broad,  flattened  ambulacral  ridges  alternating 
with  narrow  inter  ambulacral  depressions;  apex  excentric  anteriorly,  in  front  of  depressed 
apical  system;  lower  surface  shghtly  concave.  Ambulacral  petals  large,  broad,  tumid,  espe- 
cially near  apical  system ;  poriferous  zones  narrow,  at  first  diverging,  then  converging  slightly 
from  one-fourth  to  one-third  the  way  to  the  margin,  and  again  diverging  to  the  wide-open  ends 
which  are  nearly  at  the  margin.  Peristome  central;  the  main  ambulacral  grooves  straight, 
well  defined,  and  rather  deep  from  peristome  to  margin  and  continuing  as  faint  lines  over 
margin  to  near  apex,  two  faint  Unes  are  given  oflf  about  halfway  to  margin,  which  continue 
over  margin  to  near  apical  system.     Periproct  small,  inframarginal,  almost  marginal. 

Dimensions. — Specimen  B:  Length  57  millimeters ;  width  50  miUimeters;  height  14 
millimeters. 

Description. — This  species  was  one  of  the  first  of  the  Tertiary  echinoids  to  be  reported 
from  the  Pacific  coast  of  the  United  States,  having  been  described  by  Conrad  as  early  as  1S56. 
Conrad  founded  his  new  genus  Astrodapsis  upon  this  species.  The  test  is  medium  in  size, 
averaging  about  2  inches  in  length.  In  mai-ginal  outUne  it  is  regularly  oval,  longer  than 
broad,  usually  slightly  truncated  at  the  anterior  end  and  somewhat  pointed  at  the  posterior 
end,  with  very  slight  notches  opposite  the  ends  of  the  petals ;  margin  rounded  and  very  thick, 
almost  equal  in  thickness  to  the  rest  of  the  test,  somewhat  thicker  anteriorly  than  poste- 
riorly. The  whole  form  considerably  depressed,  subdiscoidal;  the  upper  surface  with  broad 
flattened  ambulacral  ridges  alternating  with  narrow  interambulacral  depressions;  apex  excen- 
tric anteriorly  in  front  of  apical  system;  under  surface  shghtly  concave. 

The  ambulacral  areas  are  wide;  dorsal  portions  petaloid.  The  petals  are  large,  broad, 
tumid,  widest  and  most  tumid  near  the  apical  system,  constituting  broad  ridges,  all  of  them 
extending  nearly  to  the  margin,  wide  open  at  the  ends ;  interporif erous  areas  very  wide ;  porif- 
erous zones  narrow  and  of  nearly  equal  breadth  throughout  their  length,  at  first  diverging, 
then  converging  shghtly  from  one-fourth  to  one-third  the  way  from  the  mai^in,  and  again 
diverging;  inner  row  of  pores  round,  outer  row  broadly  shthke,  paire  of  pores  conjugated. 

The  interambulacral  areas  are  narrow,  decidedly  depressed,  forming  radial  grooves  in 
the  upper  surface.  The  whole  surface  of  the  test  is  covered  with  small  but  conspicuous 
tubercles,  which  make  the  surface  feel  rough;  they  are  larger  and  more  conspicuous  in  the 
interporif  erous  areas. 

The  apical  system  is  shghtly  excentric  anteriorly,  in  a  star-shaped  depression  below  the 
level  of  the  ambulacral  ridges.  There  appear  to  be  only  four  genital  pores  wliich  are  located 
at  four  of  the  points  of  the  star-shaped  depression.     No  further  details  could  be  made  out. 

The  peristome  is  central,  circular  to  subpentagonal.  The  main  ambulacral  gi-ooves  are 
straight,  well  defined  and  rather  deep  from  peristome  to  margin  and  continue  as  faint  lines  over 
the  margin  and  along  the  middle  of  the  ambulacral  ridges  to  the  apical  system;    two  faintly 


MIOCENE    ECHINODEEMATA.  199 

defined  processes  are  given  off  about  halfway  from  the  peristome  to  the  margin,  whicli  extend 
to  and  over  tlie  margin  and  on  the  upper  surface  between  the  top  of  the  ridges  and  the  bottom 
of  the  depressions,  becoming  indistinct  as  the  apical  system  is  approached. 

The  periproct  is  small,  subciiTular,  inframarginal,  almost  marginal. 

Related  forms. — Duncan'  regarded  Conrad's  genus  Astrodapsis  as  a  synonym  of  Breynius's 
genus  Arachnoides;  but,  though  there  are  certain  points  of  resemblance,  the  inframarginal 
position  of  the  periproct,  the  more  or  less  depressed  apical  system  and  the  elevated,  ridgeUke 
ambulacral  areas  alternating  with  depressed  groovelike  interambulacral  areas  on  the  upper 
surface  would  appear  to  sufficiently  differentiate  the  genus  Astn)dapsis. 

The  present  species  is  readily  separated  from  the  other  representatives  of  the  genus, 
although  some  confusion  has  arisen  in  the  literature  and  in  various  collections  because  of  the 
obscure  location  of  Conrad's  description  and  figures.  A.  whitneyi  differs  in  being  broadly  sub- 
conical  and  in  ha%ang  a  thin  margin,  more  circular  outline,  more  pronounced  marginal  notches, 
higher  ambulacral  ridges  and  deeper  interambulacral  depressions.  A.  tumidus  differs  in  being 
smaller  and  in  having  a  greater  difference  between  the  height  of  the  ambulacral  ridges  and 
interambulacral  depressions. 

Localities. — Monterey  County  (type),  and  2  miles  south  of  San  Lucas,  Monterey  County 
(specimen  B),  Cal.  Conrad  also  cites  Estrella,  and  Gabb  gives  near  Buena  Vista  Lake,  both  in 
■Califorma. 

Geologic  horizon. — Santa  Margarita  formation,  middle  or  upper  Miocene. 

Collection.—U.  S.  National  Museum  (165466,  A;  16.5466a,  B).  (Both  the  type  and  the 
specimens  collected  by  Ai'iiold,  which  include  si^ecimens  A  and  B.) 

Astrodapsis  arnoldi  Twitchell,  n.  sp. 

Plate  XCV,  figure  1. 

Astrodapsis  whitneyi  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  \o.  396,  p.  63,  PI.  XI,  fig.  1. 

Astrodapsis  antiselli  var.  arnoldi  Pack,  1909,  California  Univ.  Dept.  Geology  Bull.,  vol.  5,  No.  18,  pp.  279-281,  PI. 

XXIV,  figs.  1,  2. 
Astrodapsis  whitneyi  Stefanini,  1911,  pars,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  703. 

Determinative  characters. — Test  large,  larger  than  most  representatives  of  the  genus;  circu- 
lar in  marginal  outline;  margin  and  wide  submarginal  area  notably  thin,  undulating,  with  pro- 
nounced posterior  notches  and  less  pronounced  anterior  notches.  The  whole  form  considerably 
depressed,  greatly  and  nearly  equally  so  for  half  the  distance  from  margin  toward  the  center, 
moderately  elevated  centrally,  mth  rather  broad  and  somewhat  flattened  ambulacral  ridges 
alternating  with  broad  deep  interambulacral  depressions.  The  inner  ends  of  the  ambulacral 
ridges  ahnost  coalesce  around  the  slightly  depressed  apical  system  and  form  the  somewliat 
flattened  subcentral  apex  of  the  test.  Lower  surface  fiat  or  nearly  so.  Petals  moderately 
wide,  elongate  subelliptical,  nearly  reaclung  the  margin  where  wide  open;  imier  halves  elevated 
and  tumid,  outer  halves  depressed  and  merging  with  submarginal  area;  inner  rows  of  pores 
of  each  petal  nearlj-  parallel  for  most  of  their  length.  Peristome  small,  circular,  central;  main 
ambulacral  grooves  simple,  straight  and  deep  to  the  margin,  continuing  as  faint  lines  straight 
and  deep  over  margin  and  along  middle  of  ambulacral  ridges  nearly  to  apex;  two  faint  processes 
are  given  off  about  half  way  to  margin  wliich  continue  over  margin  and  on  upper  surface  to  near 
the  apex.     Periproct  very  small,  inframarginal,  almost  marginal. 

Dimensions. — Length  76  millimeters;  mdth  75  millimeters;  height  10  mdlimeters. 

Description. — The  test  of  this  new  Astrodapsis  is  unusuaUy  large.  In  marginal  outline  it 
is  circular;  the  margin  is  markedly  thin,  undulating,  \\'ith  well-defined  notches  opposite  the 
ends  of  the  petals,  the  posterior  notches  being  slightly  larger  than  the  anterior  pair,  which  are 
larger  than  the  odd  one;  the  submarginal  area  for  nearly  half  the  way  toward  the  center  is  also 
thin,  about  as  tliin  as  at  the  margin.  Centrally,  within  the  area  circumscribed  by  tlie  thin  and 
flattened  submarginal  area,  the  upper  surface  is  moderately  elevated  A\dth  rather  broad  and 

I  Duncan,  P.  M.,  Revision  of  genera  and  great  groups  of  tlie  Echinoidea:  Linn.  Soc.  Jour.  Zoology,  vol.  23,  p.  165,  1891. 


200  MESOZOIC    AND   CESrOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

somewhat  flattened  ambiilacral  ridges  alternating  with  broad  deep  interambulacral  depressions, 
the  central  elevation  being  flattened  on  top  around  the  slightly  depressed  apical  system.  The 
ambiilacral  ridges  ahnost  coalesce  around  the  apical  system.  The  apex  is  central  or  subcentral; 
the  lower  surface  flat  or  but  very  slightly  concave  from  margm  to  center. 

The  ambulacral  areas  are  wide,  sUglitly  wider  at  the  margin  tlian  the  interambulacral  areas, 
narromng  rapidly  to  a  point  about  midway  between  the  margin  and  the  center  of  the  test, 
where  narrower  than  the  interambulacral  areas;  dorsal  portions  petaloid.  The  petals  are  of 
moderate  widtli,  elongate  subelliptical,  long,  nearly  reaching  the  margin,  the  iiuier  half  of 
each  petal  elevated,  tumid  but  somewhat  flattened  on  top,  the  outer  half  depressed,  gradually 
broadening  and  merging  \\dth  the  flattened  submarginal  area;  the  poriferous  zones  are  narrow, 
the  inner  rows  of  pores  nearly  straight  and  parallel  for  most  of  their  length,  wide  apart  at  the 
ends,  composed  of  large,  round  openings;  outer  rows  diverging  for  about  half  the  distance  to 
tlie  margin  then  drawing  near  inner  rows,  j^ores  slitlike;  pairs  of  pores  conjugated.  The  sur- 
face of  the  odd  petal  is  sligiitlj-  higher  than  that  of  tlie  anterior  pair,  which  is  shglitly  higher 
than  that  of  the  posterior  pair. 

The  interambulacral  areas  at  the  margin  are  somewhat  narrower  than  the  ambulacral 
areas,  near  the  apex  they  are  much  narrower,  almost  obliterated;  they  become  depressed  rather 
rapidly  from  near  the  apex  to  about  halfway  to  the  margin,  whence  they  merge  with  the  flat- 
tened submarginal  area,  though  keeping  slightly  more  depressed  tlian  the  adjacent  ambulacral 
areas.  The  surface  of  the  test  is  covered  uith  small  but  rather  conspicuous  tubercles,  most 
conspicuovis  in  the  interporiferous  areas. 

The  apical  sj-stem  is  central,  slightlj'  depressed  below  the  top  of  the  ambulacral  ridges. 
The  details  could  not  be  made  out  on  the  specimen  studied. 

The  peristome  is  small,  circular,  central.  The  main  ambulacral  grooves  are  simple,  straight, 
and  deep  from  peristome  to  margin;  they  continue  as  faint  Unes  over  the  margin,  and  along 
the  middle  of  tlie  ambulacral  ridges  nearly  to  the  apex;  two  faintly  defined  processes  are 
given  off  about  halfway  from  peristome  to  margin  which  extend  to  and  over  the  margin  and 
along  the  upper  surface  between  the  top  of  the  ridges  and  the  bottom  of  the  depressions,  near 
the  suture  line  between  tlie  ambulacral  and  interambulacral  plates,  disappearing  near  the 
inner  ends  of  the  mterambulacral  depressions. 

The  periproct  is  very  small,  inframarginal,  almost  marginal. 

Related  forms. — A.  arnoldi  is  most  closelj'  related  to  A.  wJiitneyi.  In  fact  specimens  of 
each  species  answer  to  Remond's  description,  and  in  view  of  the  loss  of  Remond's  type  it  is 
not  possible  to  be  sure  which  form  was  really  his.  Merriam,  evidently  influenced  by  Gabb's 
figure,  and  before  Arnold's  and  Pack's  specmiens  were  chscovered,  redescribed  and  figured  as 
A.  whitneyi  the  broadly  subcorneal  form.  Arnold's  specimen,  with  the  arch  of  the  upper  sur- 
face commencing  some  distance  in  from  the  edge,  was  identified  by  him  as  an  Astrodapsis 
whitneyi.  Pack  describes  and  figures  a  specunen  which  is  evidently  identical  with  that  of 
Arnold  just  referred  to  but  errs  in  treatmg  it  as  a  variety  of  A.  antiseUi,  from  which  it  differs 
considerably,  in  fact,  much  more  than  it  does  from  the  ^-1.  loMtneyi  of  Gabb  and  Merriam. 
The  present  form,  represented  by  the  specimens  of  Arnold  and  of  Pack,  appears  to  be  entitled 
to  recognition  as  a  distinct  species,  and  as  the  writer  agrees  with  Merriam  in  regarding  the 
broadly  subcorneal  form  figured  by  Gabb  as  most  probabty  Remond's  A.  tchitneyi  the  present 
species  is  named  after  Ai'nold,  who  collected  the  type  in  the  Coalinga  cUstrict,  California. 
A.  arnoldi  is  readily  distinguished  from  A.  whitneyi  in  having  the  arch  of  the  upper  surface 
commencing  almost  halfway  in  from  tJie  edge,  the  margin  and  ^vide  submarginal  area  being 
notably  tliin,  also  in  having  the  outer  portions  of  tlie  petals  greatly  depressed  and  merging 
with  the  submarginal  area,  and  the  ambulacral  ridges  somewhat  broader  and  more  flattened 
near  the  apex.  A.  antiselU  has  a  much  thicker  margin  and  is  subdiscoidal  in  form  besides 
differing  in  other  ways.  ^i.  jacalitosensis  has  its  apical  region  much  more  depressed,  and  into 
this  depression  extend  the  interambulacral  depressions;  the  odd  petal  is  higher  and  more  con- 
spicuous and  the  inner  lines  of  pores  of  the  petals  diverge  instead  of  being  nearly  parallel. 


MIOCENE   ECHIKODERMATA.  "  201 

Localities. — Above  Big  Blue,  west  of  Peerless  Oil  pi'operty,  9  miles  north  of  Coalinga 
(type),  and  Salinas  Valley,  Monterey  County,  Cal. 

Geologic  horizon. — Santa  Margarita  formation,  middle  or  upper  Miocene. 
Collections. — U.  S.  National  Museum  (1G5594);  Universitj"  of  California. 

AsTRODAPSis  wHiTNEYi  Remond. 
Plate  XCV,  figures  2a-c. 

Astrodapsis  whitneyi  Esmond,  1863,  California  Acad.  Nat.  Sci.  Proc,  vol.  3,  p.  .52;  no  figure. 

Aslrodapsis  whitneyi  Meek,  1S64,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

Astrodapsis  whilnetji  Gabb,  1869,  California  Geol.  Survey  Kept.,  Paleontology,  vol.  2,  pp.  37,  110,  PL  XIII,  figs.  67,  67a. 

Astrodapsis  whitneyi  Cooper ,  1888,  State  Mineralogist  of  California  Seventh  Rept.,  p.  271. 

Astrodapsis  whitneyi  Merriam,  1899,  California  Acad.  Sci.  Proc,  3d  ser..  Geology,  vol.  1,  No.  5,  p.  167,  PL  XXI,  figs. 

4,  4a. 
non  Astrodapsis  whitneyi  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  396,  p.  63,  PL  XI,  fig.  1.     See  Astrodapsis  arnoldi. 
Astrodapsis  whitneyi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  703. 

Determinative  characters. ^-Test  medium  to  large;  circular  in  marginal  outline,  broadly 
subconical  in  general  form;  margin  thin,  with  small  subequal  ambulacral  notches.  Upper  sur- 
face rising  directly  from  margin  to  the  relatively  high,  slightly  anteriorly  excentric  apex;  with 
high,  narrow,  steep-sided  ambulacral  ridges  alternating  with  broad,  deep  interambulacral 
depressions.  Lower  surface  concave.  Petals  relatively  narrow,  elongate  subelliptical,  nearly 
reaching  margin,  wide  open  at  ends;  inner  rows  of  pores  nearly  parallel  for  most  of  their  length. 
Apical  system  slightly  excentric  anteriorly,  faintly  depressed  below  top  of  petals.  Peristome 
central;  main  ambulacral  grooves  simple,  straight,  and  deep  to  the  margin,  continuing  as  faint 
lines  on  upper  surface  nearly  to  apex;  two  faint  processes  given  off  about  halfway  to  margin, 
which  also  continue  to  and  over  margin  and  on  upper  surface  nearly  to  apex.  Periproct  small, 
subcircular,  inframarginal,  almost  marginal. 

Dimensions. — Length  50  millimeters;  width  50  millimeters;  height  13  millimeters. 

Description. — This  species  was  one  of  the  first  fossil  echinoids  to  be  reported  from  the 
California  Tertiary  deposits,  having  been  described,  but  not  figured,  by  Remond  in  1863.  The 
test  is  medium  to  large,  ranging,  according  to  Merriam,  up  to  65  millimeters  in  diameter.  In 
marginal  outline  it  is  circular;  margin  thin,  with  small  but  well-defined,  subequal  notches  oppo- 
site all  the  ambulacral  petals.  The  whole  form  is  depressed,  but  less  so  than  in  related  species, 
the  upper  surface  being  broadly  subconical,  rising  directly  from  the  margin  to  the  relatively 
high,  slightly  anteriorly  excentric  apex;  with  high,  narrow,  steep-sided  ambulacral  ridges  alter- 
nating with  broad,  deep,  interambulacral  depressions.  The  under  surface  is  concave,  the  con- 
cavity gradually  deepening  to  the  peristome,  where  it  is  about  one-third  of  the  height  of  the 
test. 

The  ambulacral  areas  are  wide,  wider  than  the  interambulacral  areas;  dorsal  portions 
petaloid.  The  petals  are  relatively  narrow,  elongate  subelliptical,  long,  nearly  reaching  the 
margin;  the  poriferous  zones  are  narrow,  about  half  as  wide  as  the  tumid  interporiferous  areas, 
the  inner  rows  of  pores  elevated,  nearly  straight,  and  parallel  for  most  of  their  length,  wide  apart 
at  the  ends,  composed  of  large,  round  openings;  outer  rows  depressed,  diverging  for  about  half 
the  distance  to  the  margin,  then  drawing  near  the  inner  rows,  pores  slitlike;  pairs  of  pores  con- 
jugated; several  pairs  of  pores  occur  beyond  and  diverge  from  the  ends  of  the  petals. 

The  interambulacral  areas  at  the  margin  are  somewhat  narrower  than  the  ambulacral  areas; 
near  the  apex  they  are  much  narrower,  almost  obliterated;  they  arQ  gradually  depressed  from 
near  the  apex  to  the  margin.  The  surface  of  the  test  is  covered  with  small,  inconspicuous 
tubercles,  varying  in  size  and  set  in  shallow  scrobicules;  the  tubercles  are  somewhat  larger  in 
the  interporiferous  areas  than  elsewhere. 

The  apical  system  is  slightly  excentric  anteriorly,  faintly  depressed  below  the  tops  of  the 
ambulacral  petals.     The  details  could  not  be  matle  out  on  the  specimen. 

The  peristome  is  ceiitral.  The  main  ambulacral  grooves  are  simple,  straight,  and  deep 
from  peristome  to  margin;  they  continue  as  fainter  lines  over  the  margin  and  along  the  middle 


202  MESOZOIC   AlfD   CENOZOIC    ECHINODEKMATA    OF    THE    UNITED    STATES. 

of  the  ambulacral  ridges  nearly  to  the  apex;  two  faintly  defined  processes  are  given  off  about 
halfway  from  peristome  to  margin,  which  extend  to  and  over  the  margin  and  on  the  upper 
surface  between  the  tops  of  the  ridges  and  bottom  of  the  depressions. 

The  periproct  is  very  small,  subcircular,  inframarginal,  almost  marginal. 

Related  forms. — As  the  location  of  the  type  is  unknown,  some  doubt  exists  as  to  the  exact 
form  which  should  be  called  A.  whitneyi.  The  species  described  under  the  name  of  A.  arnoldi 
(p.  199)  agrees  with  Remond's  description  of  ^-1.  ivhitnei/i  as  well  as  if  not  slightly  better 
than  that  described  and  figm-ed  by  Merriam  as  A.  idntneni,  which  is  here  adopted.  However, 
Gabb  figured  as  A.  whitneyi  a  specimen  similar  to  the  present  form,  and  the  writer  here  foUows 
Merriam  in  regarding  it  as  probably  similar  to  Remond's  original  form.  A.  whitneyi  is  most 
closely  related  to  A.  arnoldi,  which  differs  in  having  the  arch  of  the  upper  surface  commence 
nearly  halfway  in  from  the  margin  to  the  center,  in  having  a  markedly  thin  margin  and  submar- 
ginal  area,  and  the  outer  half  of  each  petal  greatly  depressed  and  merging  with  the  submarginal 
area.  A.  whitneyi  is  also  closely  related  to  A.  jacalitosensis,  which  differs  in  much  the  same  way 
as  A.  arnoldi,  and  further  in  having  a  more  deeply  depressed  apical  system,  the  interambulacral 
depressions  extending  to  and  joining  the  apical  depression,  and' the  inner  line  of  pores  of  the 
petals  diverging.  A.  whitneyi  is  also  allied  to  A.  tumidus,  which  is  smaller,  has  a  thicker  margin, 
and  a  less  defuiitely  broadly,  subconical  upper  surface. 

Localities. — Kirkers  Pass,  north  of  Mount  Diablo,  and  south  shore  of  San  Pablo  Bay,  Cal. 

Geologic  horizon. — San  Pablo  formation  (upper  part) ,  upper  Miocene. 

Collection. — University  of  California  (19426). 

AsTRODAPSis  TUMIDUS  Reniond. 

Plate  XCV,  figures  3a-b;  Plate  CVIII,  A. 

Astrodapsis  tumidus  R6moiid,  1863,  California  Acad.  Nat.  Sci.  Proc,  vol.  3,  pp.  52,  53;  no  figure. 

Astrodapsis  tumidus  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

Astrodapsis  tumidus  Gabb,  1869,  California  Geol.  Survey  Rept.,  Paleontology,  vol.  2,  pp.  37,  110,  PI.  XIII,  figs.  68,  68a. 

Astrodapsis  tumidus  Cooper,  1888,  State  Mineralogist  of  California  Seventh  Rept.,  p.  270. 

Astrodapsis  tumidus  Merriam,  1899,  California  Acad.  Sci.  Proc,  3d  ser.,  vol.  1,  No.  5,  p.  166,  PI.  XXI,  fig.  3. 

Astrodapsis  tumidus  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  703. 

Determinative  characters. — Test  small,  circular  to  oval  in  marginal  outline;  margin  thick, 
especially  opposite  petals,  faintly  notched  opposite  petals.  Whole  form  greatly  depressed; 
upper  surface  slightly  and  more  or  less  regularly  convex  from  edge  to  edge,  with  high,  moder- 
ately wide  ambulacral  ridges  alternating  with  rather  narrow  interambulacral  depressions.  The 
ridges  are  conspicuous  for  two-thirds  the  way  from  center  to  margin,  then  become  nearly  flush 
with  the  adjacent  surfaces;  the  depressions  extend  down  the  middle  of  the  interambulacral 
areas  from  apex  to  margin,  widening  between  the  petals.  Apex  low,  subcentral;  under  surface 
slightly  concave.  Petals  wide  in  proportion  to  length,  subelliptical,  nearly  reaching  the  margin; 
poriferous  zones  about  one-third  width  of  tumid  interporiferous  areas,  inner  row  of  pores  ele- 
vated, outer  row  depressed.  Apical  system  subcentral,  slightly  depressed  below  tops  of  petals. 
Peristome  small,  circular,  subcentral;  main  ambulacral  grooves  simple,  straight,  and  deep  to 
margin,  continuing  over  margin  and  nearly  to  apex  as  a  faint  line.  Periproct  very  small,  cir- 
cular, inframargmal,  almost  marginal. 

Dimensions. — Length  30  millimeters;  width  30  millimeters;  height  8  millimeters. 

Description. — This  species  is  one  of  the  earliest  reported  Pacific  coast  fossil  echinoids,  having 
been  described,  but  not  figured,  by  Remond  in  1S63.  The  test  is  small,  rarely  exceeding  IJ 
inches  in  diameter.  In  marginal  outline  it  is  somewhat  variable,  though  usually  oval  or  circu- 
lar; miargin  moderately  thick  and  rounded,  quite  thick  opposite  the  ends  of  the  petals,  where 
equal  to  more  than  half  the  height  of  the  test,  with  faint  notches  opposite  the  ends  of  the  petals. 
The  whole  form  is  greatly  depressed ;  the  uf)per  surface  slightly  ami  more  or  less  regularly  convex 
from  edge  to  edge,  with  high,  moderately  wide  ambulacral  ridges,  which  are  conspicuous  for 
two-thirds  of  the  way  from  the  center,  alternating  with  rather  narrow,  deep,  interambulacral 
depressions.     The  apex  is  low,  subcentral;  under  surface  slightly  concave. 


MIOCENE   ECHINODERMATA.  203 

Tho  ambulacral  petals  are  relatively  wide  in  proportion  to  their  length,  subelliptical, 
nearly  reaching  the  mai-gin,  wde  open  at  the  ends,  inner  two-thirds  or  more  tumid  and  promi- 
nent, outer  ends  nearly  flush  with  the  adjacent  surfaces;  poriferous  zones  narrow,  about  one- 
thhd  the  width  of  the  interporiferous  areas;  the  inner  row  of  pores  elevated,  pores  round, 
outer  row  depressed,  pores  slitlike,  pairs  of  pores  conjugated. 

The  inter  ambulacral  areas  are  deeply  depressed  along  the  middle  from  apex  to  margin. 
The  surface  of  the  test,  including  the  margm  and  interporiferous  areas  is  covered  with  small, 
conspicuous  tubeicles  in  deep  scrobicules. 

The  apical  system  is  subcentral,  slightly  but  distinctly  depressed  below  the  tops  of  the 
petals.     ITie  details  could  not  be  made  out  on  the  specimen. 

The  peristome  is  small,  circular,  subcentral.  The  main  ambulacral  grooves  are  simple, 
straight,  and  deep  from  peristome  to  margin,  continuing  as  faint  Imes  over  the  margin  and 
along  the  ambulacral  ridges  nearly  to  the  apex.  The  two  faint  processes  usually  given  off 
from  the  main  grooves  on  species  of  this  genus  could  not  be  clearly  made  out  on  the  specimen 
studied. 

The  periproct  is  very  small,  circular,  inframarginal,  almost  marginal. 

Related  forms. — A.  tumulus  is  most  closely  related  to  A.  whitneyi,  but  has  a  thicker  margia, 
especially  opposite  the  ends  of  the  petals,  is,  in  general,  smaller,  lower,  and  not  subcorneal,  has 
only  famt  marginal  notches,  petals  which  are  broader  in  proportion  to  their  length,  a  more 
depressed  apical  system  and  a  less  concave  lower  surface.  A.  tumulus  presents  some  features 
similar  to  A.  antiselli,  which  make  descriptions  sound  alike;  but  the  forms  are  quite  distinct, 
A.  tumulus  bemg  readily  distinguished  by  its  smaller  size,  less  thickness,  much  narrower  and 
higher  ambulacral  ridges,  and  wider  interambulacral  depressions. 

Localities. — Kirkers  Pass  and  2  miles  west  of  Walnut  Creek  House  (Remond);  San  Pablo 
Bay,  Cal.  (Merriam). 

Geologic  liorizon. — San  Pablo  foi'mation  (middle  part),  upper  Miocene. 

Collection. — -University  of  California  (19424). 

AsTRODAPSis  JACALiTosENSis  Arnold. 

Plate  XCV,  figure  4. 

Astrodapds  jacalitosensis  Arnold,  1909,  U.  S.  Geol.  Survey  Bull.  39G,  pp.  63-64,  PI.  XV,  fig.  5. 
Astrodapsis  jacalitosensis  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  703. 

Determinative  characters. — Test  large;  broadly  subovate  in  marginal  outline,  broadest 
posteriorly;  margin  thin,  deeply  notched  opposite  the  posterior  petals.  The  whole  form  con- 
siderably depressed,  gi'eatly  and  equally  so  for  half  the  way  in  from  edge;  centrally  the  upper 
surface  is  higher,  with  conspicuous  ambulacral  ridges,  of  which  the  odd  anterior  one  is  the 
highest,  thus  forming  the  anteriorly  excentric  apex  of  the  test,  and  pronounced  interambu- 
lacral depressions  which  merge  with  the  deep  depression  in  the  apical  region,  the  posterior 
depression  being  deeper  and  narrower  than  the  rest.  Petals  tumid  and  elevated  proximally, 
depressed  distally;  inner  rows  of  pores  div.^rging  in  nearly  straight  lines  to  near  the  margin, 
where  wide  apart  outer  row  curving  at  first  away  from  and  then  toward  the  inner  row.  Apical 
system  excentric  anteriorly,  deeply  depressed.  Details  of  lower  sm-face  could  not  be  made 
out.     Periproct  small,  inframarginal,  almost  marginal. 

Dimensions. — Length  77  millimeters;  width  74  millimeters;  height  15  millimeters. 

Description. — This  new  Astrodapsis,  which  Arnold  regards  as  a  characteristic  fossil  of  the 
Jacalitos  formation  in  California,  is  large  in  size,  being  one  of  the  largest  representatives  of  the 
genus.  In  marginal  outline  it  is  bi'oadly  subovate,  broadest  posteriorly,  slightly  longer  than 
wide,  -svith  deep  notches  opposite  the  posterior  petals  and  faint  notches  opposite  the  other 
petals;  margin  thin.  TTie  whole  form  is  considerably  depressed,  the  marginal  and  submargi- 
nal  areas  greatly  so  and  about  evenly  so  all  around.  Within  the  inner  portion  of  the  petaloidal 
region  there  are  alternating  ambulacral  ridges  and  interambulacral  depressions.  The  depres- 
sions extend  to  and  niei'ge  with  the  deep  depression  in  the  apical  region,  the  posterior  depression 


204  MESOZOIC   AND   CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

being  deeper,  narrower,  and  more  pronounced  than  the  rest.  The  ridges  are  all  conspicuous, 
but  the  odd  anterior  one  is  the  highest  and  most  pronounced,  constitutmg  the  anteriorly  excen- 
tric  apex  of  the  test.     The  details  of  the  under  surface  could  not  be  made  out  on  the  specimen. 

The  aml)ulacral  areas  are  wide,  slightly  wider  than  the  interambulacral  areas  at  the  mar- 
gin; dorsal  portions  subpetaloid.  The  inner  parts  of  the  peatals  are  tumid  and  elevated, 
the  outer  parts  depressed.  The  inner  rows  of  pores  gradually  and  continuously  diverge  to  about 
one-fourth  inch  from  the  margin.  Tlie  outer  rows  first  diverge  and  then  converge  around  the 
tumid  parts  of  the  petals  and  approach  near  to  the  inner  row,  beyond  which  point  both  rows 
diverge  slightly  to  the  margin.  The  inner  rows  of  pores  are  large  and  round,  the  outer  rows 
oval.  There  are  one  or  two  extra  rows  of  pores  within  the  main  inner  row.  The  pairs  of  pores 
are  conjugated. 

The  apical  system  is  excentric  anteriorly,  decidedly  depressed  below  the  surface  of  the 
petals.     The  details  could  not  be  made  out. 

The  under  surface  not  being  exposed  the  details  in  regard  to  the  peristome  and  ambulacral 
grooves  can  not  be  given.     The  pcriproct  is  small,  inframarginal,  almost  mai-ginal. 

Related  forms. — A.  jacalitosensis  is  most  closely  related  to  A.  arnoMi,  which  differs  in 
having  a  less  depressed  apical  region  and  not  having  the  interambulacral  depressions  continu- 
ing to  and  joining  the  apical  depression;  also  in  having  the  inner  rows  of  pores  of  each  petal 
nearly  parallel. 

Locality. — -South  of  Garza  Creek,  a  mile  southeast  of  Clark's  place,  Coalinga  district,  Cal. 

Geologic  horizon. — -Jacalitos  formation,  upper  Miocene. 

Collection.— U.  S.  National  Museum  (165610). 

Genus  MELLITA  Agassiz. 

Mei.lita  cakolixiaxa  Ravenel. 

Plate  XCI,  figures  la-b;  Plate  XCII,  figures  la-b. 

Scutella  caroUniana  Ravenel,  1841,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.,  vol.  8,  pp.  333,  334,  text  figure. 

non  MellUa  hexapora  L.  Agassiz,  1841,  Mon.  ^chiuodermes  vivans  et  fossiles;  Des  scutelles,  p.  41,  PI.  IV,  figs.  11, 12. 

ilellita  caroUniana  Ravenel,  1848,  Echinidse,  recent  and  fossil,  of  South  Carolina,  p.  160. 

Scutella  carolinensis  Tuoniey,  1848,  Geology  South  Carolina  Rept.,  p.  208, 

Ilellita  caroUniana  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 

Mellita  caroUniana  Tuomey  and  Holmes,  1855,  Pliocene  fossils  South  Carolina,  pp.  3,  4,  PI.  I,  fig.  4. 

non  Mellita  hexapora  Desor,  1858,  Synopsis  des  echinides  fossiles,  p.  237. 

Mellita  caroliniata  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

Mellita  caroUniana  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  74. 

Mortonia  {Periarchus)  carolinensis  Conrad,  1866,  Smithsonian  Misc.  Coll.,  vol.  7  (200),  p.  21. 

non  Mellita  sexforis,  A.  Agassiz,  1872,  Revision  of  the  Echini,  pp.  141,  320. 

non  Mellita  sexforis  Gregory,  1891,  Geol.  Soc.  America  Bull.,  vol.  3,  p.  107. 

Scutella  caroUniana  Boyle,  1893,  U.  S.  Cieol.  Survey  Bull.  102,  p.  262. 

Periarchus  carolinensis  ?  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  699. 

Mellita  caroUniana  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  708. 

Determinative  characters. — Test  small  to  very  large;  subcircuhir  to  subpentagonal  in  mar- 
ginal outUne,  broadest  between  the  anterior  and  posterior  pairs  of  petals;  six  lunules,  the  odd 
posterior  one  much  longer  than  the  posterior  pair  which  are  longer  than  the  rest ;  margin  thin ; 
the  whole  form  greatly  depressed,  the  upper  surface  rising  gradually  and  but  sHghtly  from  the 
margin  to  the  very  low,  subcentral  or  posteriori}^  excentric  apex;  under  surface  flat.  Ambu- 
lacral petals  large,  the  posterior  pair  longer  than  the  othei-s.  Apical  system  excentric  ante- 
riorly. Peristome  small,  subcircular,  excentric  anteriorly;  ambulacral  furrows  simple  and 
straight  near  tlie  peristome,  then  forking,  each  pair  of  branches  diverging  and  again  converging 
near  the  margin.  Periproct  very  small,  elliptical,  between  the  inner  end  of  the  odd  posterior 
lunule  and  the  peristome. 

Dimensions. — The  large  form  figured  gave:  Length  159  millimeters;  width  152  millimeters; 
height  about  10  miUimeters. 


MIOCENE   ECHINODEKMATA.  205 

Description. — This  beautiful  Mellita,  first  reported  and  described  by  Ravenel  in  1S41,  is 
probably  the  oldest  representative  of  the  genus,  as  it  undoubtedly  existed  in  America  in  Mio- 
cene time.  Hitherto  the  genus  has  not  been  positively  known  to  have  existed  prior  to  the 
Pliocene.  The  species  is  rather  rare,  only  a  few  specimens  having  been  reported  up  to  the 
present  time.  The  test  is  small  to  very  large  in  size,  ranging  from  1  to  6  inches  in  diameter. 
In  marginal  outline  it  is  somewhat  variable,  being  either  subcircular,  subpentagonal,  or  broadly 
subovate.  It  is  usually  about  as  long  as  broad;  broadest  between  the  anterior  and  posterior 
pair  of  petals,  usually  about  the  middle,  but  sometimes  back  of  the  middle  of  the  test ;  rounded 
or  truncated  posteriorly.  There  are  six  lunules,  one  opposite  each  petal  and  very  near  the 
margin  and  one  in  the  middle  of  the  posterior  ambulacrum,  distant  from  the  margin.  The 
three  anterior  lunules  are  short  and  either  pyriform  or  narrowly  oblong,  the  posterior  pair 
longer  and  usually  narrowly  oblong,  and  the  odd  posterior  one  much  longer  and  frequently 
wider  than  all  of  the  others,  and  either  narrowly  oblong  or  elongate  subpyriform  or  elongate 
subelliptical.  In  yomig '  specimens  the  odd  posterior  lunule  is  much  longer  and  more  con- 
spicuous relatively  than  in  older  ones.  The  whole  form  is  greatly  depressed,  the  upper  surface 
rising  gradually  from  the  margin  to  the  very  low  apex  which  is  either  central,  slightly  excentric 
anterioily  or  excentric  posteriorly,  and  rarely  rises  to  a  height  of  half  an  inch  in  even  the  largest 
specimens.  The  margin  is  thin,  sometimes  with  faint  notches  opposite  the  posterior  paired 
petals.     The  under  surface  is  flat,  or  nearly  so. 

The  ambulacral  areas  are  relatively  narrow  in  the  petaloid  dorsal  portions,  wide  between 
the  ends  of  the  petals  and  the  margin  where  they  are  wider  than  the  interambulacral  areas, 
narrowing  again  at  the  margin.  The  petals  are  large,  and  somewhat  variable,  extending  half- 
way or  decidedly  more  or  less  than  halfway  to  the  mai'gin;  subelliptical  to  subspatulate  in  form; 
usually  narrower  than  those  of  Mellita  pentapora;  the  posterior  pair  longer  than  the  others, 
which  are  subequal  in  length.  The  poriferous  zones  are  broad,  equal  to  or  broader  than  the 
interporiferous  areas;  pores  oval,  pairs  of  pores  conjugated  by  very  narrow,  flexuous  grooves. 

The  interambulacral  areas  are  broad,  broadest  at  the  margin,  where  they  are  wider  than 
the  ambulacral  areas.  The  surface  of  the  test  is  closely  set  with  very  small,  imperforate 
tubei'cles,  set  in  deep  scrobicules.  The  tubercles  are  larger  on  the  under  siirface  except  along 
and  near  the  ambulacral  furrows. 

The  apical  system  is  excentric  anteriorly,  large  and  stellate;  four  genital  pores  at  the  tips 
of  the  points  of  the  star,  the  two  posterior  farthest  apart;  five  small  pores  at  the  inner  ends  of 
the  reentrant  angles  of  the  star. 

The  peristome  is  small,  subcii'cular,  excentric  anteriorly;  the  ambulacral  furrows  simple 
and  straight  near  tlie  peristome,  then  forking,  each  pair  of  branches  diverging  and  again  con- 
verging near  the  margin  so  as  to  surround  the  lunules. 

The  periproct  is  very  small,  elliptical,  between  the  inner  end  of  the  odd  posterior  lunule 
and  the  peristome. 

Related  forms. —  M.  caroliniana  is  closely  related  to  M.  pentapora,  which  is  readily  sepa- 
rated by  its  having  only  five  lunules,  by  the  greater  height  and  mere  anterior  position  of  its 
apex,  and  by  having  its  lunules  subequal  in  length  and  farther  from  the  margin.  M.  caroliniana 
is  still  more  closely  related  to  the  n^cent  species  M.  sexforis  A.  Agassiz,  which,  however,  diflFers 
in  having  its  five  ambulacral  lunules  oU  of  the  same  length  and  its  odd  posterior  lunule  a  little 
shorter  than  the  others;  another  difference  is  that  the  distance  between  the  pairs  of  food  grooves 
in  M.  sexforis  is  greater  than  it  is  in  M.  caroliniana. 

Localities. — Ravenel's  type  came  from  The  Grove,  Cooper  River,  17  miles  from  Charleston, 
S.  C.  The  large  form  figured  in  this  paper  came  from  South  Carohna;  but  the  exact  locaUty  is 
not  known.  Other  localities  are  Goose  Creek,  Cooper  River,  and  Bostick  Landing,  Great 
Peedee  River,  S.  C. ;  Wihnington,  and  .3  miles  north  of  Grif ton,  Pitt  County,  N.  C. ;  Yorktown,  Va. 

Geologic  horizon. — Duplin  marl  in  South  Carolina,  and  Yorktown  formation,  in  North 
Carohna  and  Virginia,  both  upper  Miocene. 

Collections. — Academy  of  Natural  Sciences  of  Philadelphia  (10S.3);  American  Museum  of 
Natural  History;  U.  S.  National  Museum. 
39800°— 15 14 


206  MESOZOIC   AND   CENOZOIC   ECHINODEKMATA    OF    THE    UNITED    STATES. 

Genus  SCUTASTER  Pack. 

Scutaster  Pack,  1909,  California  Univ.  Dept.  Geology  Bull.,  vol.  5,  No.  18,  p.  278,  PI.  XXIII,  fig.  2. 

Description. — Test  circular  depressed,  ambulacral  star  small.  Lunules  in  the  prolongation 
of  the  petals  of  the  trivium,  and  either  lacking  in  the  bivium  and  posterior  interambulacral 
space  or  not  placed  in  the  same  relative  positions  as  on  the  anterior  portion  of  the  test  (Pack). 

This  genus  was  founded  on  a  single  imperfect  specimen  found  in  the  Aliocene  deposits  of 
Cahfornia,  which  is  also  the  t3'pe  of  the  following  species.  Judging  from  the  single  figure  M-liich 
Pack  gives,  there  are  good  grounds  for  beheving  that  the  new  genus  should  be  recognized.' 

Scutaster  andersoni  Pack. 

Plate  XCIII,  figure  1. 

ScutasUr  andersoni  Pack,  1909,  CaUforiiia  Univ.  Dept.  Geology  Bull.,  vol.  5,  No.  18,  pp.  278-279,  PI.  XXIII,  fig.  2. 
Scutaster  andersoni  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  704. 

Description. — Only  a  single  imperfect  specimen  of  this  species  is  known  to  exist/  and  as 
the  Avriter  has  had  no  opportunity  of  studying  it,  the  description  of  Pack  is  given  verbatim: 

Test  subcircular  in  outline,  edges  markedly  thin.  Upper  surface  regularly  arched  from  the  margin;  apex  anterior 
to  the  center.  Apical  system  small  and  apparently  central.  Ambulacral  star  small;  petals  extending  sUghtly  less 
than  halfway  to  the  margin  of  the  test,  closed  at  the  ends.  Lateral  petals  broader  than  the  posterior  ones,  but  of  almost 
the  same  length.  Poriferous  zones  broad,  and  continuing  full  width  almost  to  the  ends  of  the  petals.  In  the  posterior 
petals  the  interporiferous  area  forms  about  one-third  the  width  of  the  petal.  Poriferous  zones  of  the  lateral  petals 
equal  in  width  to  those  of  the  posterior  petals,  but  inclosed  area  broader.  In  the  extension  of  the  three  anterior  petals 
are  broad  lunules,  over  half  as  long  as  the  petals;  shallow  grooves  extend  from  the  lunules  to  the  margin.  Anterior 
lunule  slightly  farther  from  the  apical  system  than  are  the  lateral  ones.  From  the  ends  of  the  posterior  petals  the 
plates  enlarge  and  the  area  broadens  rapidly.  No  lunules  were  seen  here,  nor  in  the  posterior  interambulacral  space. 
They  may  be  represented  by  marginal  notches,  as  the  posterior  edge  of  the  specimen  is  lacking. 

Dimensions. — Transverse  diameter  44  mUlimeters;  height  8  millimeters. 
Locality. — East  of  Muir,  Contra  Costa  County,  Cal. 
Geologic  horizon. — Miocene. 
Collection. — University  of  California. 

Genus  ENCOPE  Li.  Agassiz. 
Encope  macrophora  Ravenel. 

Plate  XCIII,  figures  2a-e;  Plate  XCIV,  figures  la-f,  2. 

Saitella  macrophora  Ravenel,  1842,  Acad.  Nat.  Sci.  Philadelphia  Jour.,  1st  ser.,  vol.  8,  pt.  2,  pp.  334,  335,  text  figure. 

Encope  macrophora  Ravenel,  1S48,  Echinidse,  recent  and  fossil,  of  South  Carolina,  p.  2. 

Scutella  macrophora  Tuomey,  1848,  Geology  South  Carolina  Rept.,  p.  208. 

Encope  macrophora  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 

Encope  macrophora  Tuomey  and  Holmes,  1855,  Pliocene  fossils  of  South  Carolina,  pp.  2,  3,  PI.  I,  fig.  3. 

Non  Scutella  hexapora  Desor,  1858,  Synopsis  des  echinides,  p.  237.     Desor  e^idently  meant  to  give  5.  caroliniana 

Ravenel  as  a  synonym  of  S.  hexapora  but  gave  S.  macrophora  instead. 
Encope  macrophora  Meek,  1864,  Smithsonian  ilisc.  Coll.,  vol.  7  (183),  p.  2. 

Rarenellia  macrophora  Lutken,  1863,  Bid.  til  Kunds.  om  Echinoderme;  Vidensk.  Medd.  Kjabenhavn. 
Macrophora  macrophora  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  74. 
Macrophora  raveneli  Conrad,  1865,  Acad.  Nat.  Sci.  Philadelphia  Proc,  p.  74. 
Ravenellia  macrophora  Agassiz,  1883,  Mus.  Comp.  Zoology  Mem.,  vol.  10,  No.  1,  p.  89. 
Scutella  macrophora  Boyle,  1893,  U.  S.  Geol.  Survey  Bull.  102,  p.  263. 
Encope  macrophora  Stefanini,  1911,  Soc  geol.  italiana  Boll.,  vol.  30,  p.  70S. 

1  Since  the  above  descriptions  were  written  Pack  has  published  some  new  information  regarding  this  unique  Californian  form,  based  on 
material  recently  discovered  (California  Univ.  Dept.  Geology  Bull.,  vol.  7,  No.  13,  pp.  300-302,  ri.  XV,  figs.  2a-b,  1913).  The  new  data  establish 
the  genus  Scutaster  on  a  firm  basis.  It  is  characterized  by  having  but  three  lunules,  which  are  situated  in  the  anterior  ambulacral  areas.  The 
new  specimens  show  that  Scutaster  andersoni  is  transversely  suboval  in  marginal  outline,  with  narrow  notches  opposite  the  three  anterior  petals 
and  broad  shallow  notches  opposite  the  posterior  pair.  The  apex  is  anteriorly  and  the  apical  system  posteriorly  excentric.  Longitudinal 
diameter  53  millimeters;  transverse  diameter  C2  millimeters;  height  5  to  6  millimeters.  The  new  locality  is  on  the  north  slope  of  the  San 
Emigdio  Mountains,  at  the  southern  end  of  the  San  Joaquin  Valley,  where  the  tests  are  said  to  occur  in  great  abundance.  In  regard  to  geologic 
horizon  Pack  says,  "known  only  in  the  lower  half  of  the  Miocene." 


MIOCENE  ECHIjSTODEEMATA.  207 

Determinative  characters. — Test  small  to  large  in  size,  suboval  to  subovate  in  marginal 
outline;  truncated  or  convex  posteriorly;  shallow  notches  opposite  the  anterior  petals,  deep 
ones  opposite  the  posterior  pair;  one  large  lunule  in  the  posterior  interambulacrum ;  margin 
tliick;  much  depressed,  being  low  and  nearly  flat  along  the  front  and  sides,  but  rising  toward 
the  center  and  posteriorly  in  a  low  longitudinally  elongate  mound.  Apex  slightly  excentric 
posteriorly,  under  surface  flat.  Ambulacral  petals  large,  the  posterior  pair  longer  than  the 
rest  and  curved  around  the  lunule.  Apical  system  excentric  anteriorly.  Peristome  small, 
subcircular,  excentric  anteriorly;  ambulacral  furrows  simple  and  straight  for  a  short  distance 
from  the  peristome,  then  forking.  Periproct  very  small,  subelliptical,  at  the  edge  of  the  lunule 
nearest  the  peristome. 

Dimensions. — Specimen  A:  Length  97  millimeters;  wddth  79  millimeters;  height  IS  milli- 
meters. Specimen  B:  Length  62  millimeters;  width  5S  millimeters;  height  11  miUimeters. 
Specimen  C:  Length  .31  millimeters;  \\adth  28  millimeters;  height  .5  millimeters. 

Description. — This  handsome  species,  the  only  representative  of  the  genus  Encope  yet  reported 
from  the  Cenozoic  deposits  of  the  Atlantic  coast,  was  described  by  Ravenel  as  early  as  1842.  At 
first  he  placed  it  in  the  genus  ScuteUa,  but  a  few  years  later  assigned  it  to  the  genus  Encope. 
Both  Lutken  and  Conrad  founded  new  genera  upon  this  species,  but  there  appears  to  be  no  good 
ground  for  the  recognition  of  either.  Conrad's  new  species,  Macrophora  raveneli,  is  believed 
to  have  been  merely  a  young  specimen  of  Ravenel's  species.  This  species  is  rather  abundant 
in  a  few  localities  in  South  Carolina  and  Florida,  but  is  rare  elsewhere.  The  test  is  variable  in 
size,  ranging  from  less  than  an  inch  to  nearly  4  inches  in  longitudinal  diameter.  In  marginal 
outline  it  is  either  suboval,  somewhat  ovate  or  obovate,  or  subquadrate;  usually  broader  near 
the  posterior  end  than  near  the  anterior  end;  posterior  border  usually  truncated,  sometimes 
convex;  a  shallow  notch  opposite  the  odd  petal,  slightly  deeper  rounded  ones  opposite  the 
anterior  paired  petals,  and  large  deep  angular  ones  opposite  the  posterior  petals;  the  posterior 
notches  vary  from  a  flaring  and  subrectangular  form  in  small  specimens  to  a  less  open  and  more 
acute  form,  or  one  with  parallel  sides  in  larger  specimens.  A  large  lunule  occupies  the  larger 
part  of  the  posterior  interambulacrum,  which  varies  in  form  from  circular  in  very  small  speci- 
mens to  oval,  subovate,  or  subspatulate  in  larger  ones,  the  elongation  being  longitudinal  when 
occurring;  the  width  of  the  lunule  is  usually  greater  near  the  under  surface,  especially  in  large 
specimens.  The  whole  form,  including  the  margin,  is  thick,  particularly  so  in  large  individuals. 
The  whole  test  is  much  depressed,  being  nearly  flat  along  the  front  and  sides;  but  rising  toward 
the  center  in  a  low  longitudinafly  elongate  mound  which  extends  from  about  the  middle  of  the 
odd  petal  to  the  posterior  border.  The  height  of  the  mound  varies  directly  with  the  size  of  the 
specimen,  ranging  from  less  than  an  eighth  to  more  than  three-fourths  of  an  inch.  The  apex 
is  central  or  subcentral,  being  usually  shghtly  excentric  anteriorly,  though  sometimes  slightly 
excentric  posteriorly  at  the  summit  of  the  central  mound,  which  is  usually  the  anterior  end 
of  the  raised  and  thickened  margin  of  the  lunule.  The  depressed  marginal  area  is  more  or 
less  distinctly  corrugated  by  alternating  low  ridges  and  shaUow  troughs,  there  being  two  or 
three  troughs  between  the  notches  in  the  margin.  The  under  surface  is  flat  or  slightly  concave, 
usuaUy  increasingly  concave  near  the  margin  of  the  lunule. 

The  ambulacral  areas  are  narrow  in  the  petaloid  region,  wide  in  the  margmal  region  where 
they  about  equal  the  interambulacral  areas.  The  dorsal  portions  are  petaloid.  The  petals  are 
large,  unequal  m  length,  divisible  into  a  bivium  and  a  trivium;  those  of  the  trivium  usuaUy  sub- 
equal  in  length,  sometimes  with  the  odd  petal  shorter  than  the  other  two,  subelliptical  or  some- 
what spatulate  in  form;  those  of  the  bivium  much  longer  than  the  others,  tapering  gradually 
from  the  distal  ends  toward  the  apical  system,  gracefully  curved  around  the  lunule,  all  the  petals 
open  at  the  ends  and  extending  about  two-thirds  the  way  to  the  margin.  The  poriferous  zones 
are  wide,  as  wide  as  or  sUghtly  wider  than  the  interporiferous  areas ;  the  inner  rows  of  pores  nearly 
paraUel  and  composed  of  rather  large  oval  pores,  outer  row  of  smaUer  oval  or  elliptical  pores  at 
the  bottom  of  deepened  portions  of  very  narrow  grooves  by  which  the  pairs  of  pores  are 
conjugated. 


208  MESOZOIC   AND   CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

The  iiiterambulacral  areas,  except  the  posterior  area,  are  narrow  in  the  petaloid  region, 
wider  in  the  marginal  region;  the  posterior  interambulacral  area  is  wider  and  its  plates  differ 
considerablj'  in  form  from  those  of  the  other  areas,  because  of  the  presence  of  the  lunule.  The 
whole  surface  of  the  test  is  covered  with  small  uniform  tubercles  which  are  larger  on  the  under- 
surface  and  inside  the  lunule. 

The  apical  system  is  excentric  anteriorly,  in  front  of  and  below  the  apex  on  the  more  or  less 
steeply  sloping  anterior  side  of  the  central  mound.  The  madreporite  is  large,  stellate  or  sub- 
pentagonal,  nearly  flush  with  the  surface.  There  are  five  genital  pores  a  short  distance  away 
from  the  points  of  the  madreporic  star,  their  relative  positions  varying  somewhat,  and  five 
small  radial  plates  each  perforated  by  a  small  pore,  on  the  proximal  side  of  which  there  is  a  very 
small  swelling.  The  posterior  genital  pore  is  sometimes  somewhat  displaced  from  the  median 
line. 

The  peristome  is  small,  subcircular  to  subpentagonal,  excentric  anteriorly;  the  ambulacral 
furrows  rather  deep,  simple  and  straight  for  a  short  distance  from  the  peristome,  then  forking, 
each  pair  of  branches  diverguig  somewhat,  the  three  anterior  pairs  more  so  than  the  posterior 
two,  extending  to  the  margin  and  endmg  close  alongside  of  the  marginal  notches.  Each  branch 
gives  off  one  side  branch  on  the  outside  at  nearly  right  angles  about  halfway  from  the  peristome 
to  the  margin,  which  soon  bend  and  proceed  to  the  margin.  A  very  thin  ridge  extends  out  from 
the  peristome  along  the  middle  of  the  short  unbranched  portion  of  each  ambulacral  furrow. 

The  periproct  is  very  small,  much  smaller  than  the  peristome,  usually  elUptical  or  sub- 
elliptical,  sometimes  subcircular  or  subpjrrif orm,  situated  usually  on  the  sloping  edge  of  the  lunule 
nearest  the  peristome,  sometimes  on  the  inner  wall  of  the  lunule,  but  near  the  under  surface  of 
the  test. 

This  species  presents  variable  features  which  illustrate  in  an  interesting  way  changes  due  to 
the  development  of  the  individual.  As  the  forms  increase  in  size  and  age  the  lunule  enlarges  and 
becomes  more  elongate  and  irregular,  the  posterior  marginal  notches  become  less  flaring  and  tend 
to  close,  the  posterior  edge  changes  from  a  truncated  one  to  one  more  and  more  convexly  rounded, 
the  posterior  end  becomes  at  first  relatively  broader  then  relatively  narrower  than  the  anterior 
end,  the  height  of  the  central  mound  and  thickness  of  the  margin  increase,  the  corrugations  on 
the  upper  surface  become  more  accentuated,  and  irregularities  appear  in  the  poriferous  zones. 
Lack  of  space  forbids  a  more  complete  discussion  of  these  features  here;  but  a  comparison  of  the 
figures  given  will  bring  them  out  in  a  stronger  light.  Specimen  A,  for  instance,  presents  geruntic 
features,  the  effect  of  the  elongation  of  the  lunule  in  pushing  out  and  rounding  the  posterior 
border,  nearly  closing  the  posterior  notches  and  so  changing  the  marginal  outline  as  to  make  the 
form  seem  at  least  varietal  in  value  if  not  a  different  species. 

Related  forms . — The  only  American  fossil  echinoid  resembling  this  species  is  E.  tenuis  Kev/,^ 
from  the  upper  Miocene  or  lower  Pliocene  of  the  Pacific  coast.  ■  E.  macrophora  is  easily  separated 
by  its  larger  lunule,  shallower  anterior  notches,  posterior  petals  curving  around  the  lunule,  and 
having  the  periproct  at  the  edge  of  the  lunule.  The  recent  species  Encope  grandis  L.  Agassiz, 
reported  by  A.  Agassiz  '  from  the  Gulf  of  California,  is  the  most  closely  related  to  the  present 
form,  the  very  features  which  A.  Agassiz  notes  as  remarkable  in  E.  grandis  being  those  most 
characteristic  of  E.  macropJiora.  E.  grandis  differs,  however,  in  having  aU  five  marginal  notches, 
and  especially  the  three  anterior  ones,  larger  and  more  deeply  incised,  in  having  wider  interpo- 
riferous  areas,  and  the  posterior  margin  concave.  Encope  emarginata  Agassiz,  a  recent  species 
from  the  coast  of  Brazil  and  the  West  Indies,  is  similar  in  general  outUne  to  E.  macropTiora,  the 
young  forms  of  the  two  species  being  quite  similar,  although  the  lunule  of  the  young  E.  macro- 
phora  is  usually  more  circular  than  that  of  the  young  E.  emarginata.  The  older  forms  of  E. 
emargirmta  also  differ  in  that  the  marginal  notches  become  lunules,  a  change  which  appears 
never  to  take  place  in  E.  macrophora.  Possibly  the  present  fossil  form  may  be  ancestral  to  E. 
emarginata.  Encope  dse  De  Cartazar,  from  the  uj^per  Miocene  of  Cuba,  presents  some  points 
of  similarity  to  the  present  species,  but  its  lunule  is  smaller  and  more  rectangular  in  form,  its 

1  Revision  of  the  Echini,  p.  MS  and  PI.  XIII,  flg.  d. 

-  The  description  of  E.  tenuis  Kew  appeared  while  the  present  worli  was  in  press.  See  California  Univ.  Dept.  Geology  Bull.,  vol.  8^  No.  5, 
pp.  47-48,  PI.  I,  flg.  1,  and  PI.  II,  fig.  1,  1914. 


MIOCENE   EC^INODEEMATA.  209 

posterior  marginal  notches  are  less  pronounced  and  have  one  side  merging  into  its  more  rounded 
posterior  margin. 

Localities. — Dr.  Ravenel's  plantation,  known  as  "The  Grove,"  on  Cooper  River,  17  niiles 
from  Charleston,  and  Goose  Creek,  S.  C. ;  AlHgator  Creek,  Monroe  County,  and  near  Punta  Garda, 
Alligator  Creek,  Monroe  County,  Fla. 

Geologic  horizon. — Duplin  marl,  upper  Miocene,  in  South  Carolina,  Caloosahatchee  marl, 
Pliocene,  in  Florida. 

Collections. — Academy  of  Natural  Sciences  of  Philack^phia  ( 1086,  A) ;  U.  S.  National  Museum 
( 164658,  B;  9970,  C) ;  American  Museum  of  Natural  History;  Boston  Society  of  Natural  History; 
Wagner  Free  Institute  of  Science. 

Family  CLYPEASTRID.f]. 

Genus  CIiYPEASTER  Lamarck. 

Clypeaster  bowersi  Weaver. 

Plate  XCVI,  figures  la-b. 

Clypeaster  bowersi  Weaver,  1908,  California  Univ.  Dept.  Geology    Bull.,  vol.  5,  No.  17,  pp.  271-272,  PL  XXI,  fig.  1; 

PI.  XXII,  fig.  1. 
Clypeaster  bowersi  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  701. 

Description. — As  the  writer  has  had  no  opportunity  of  studying  the  single  specimen'  of 
this  large  Clypeaster  that  has  been  discovered  the  description  of  Weaver  is  here  given  verbatim: 

The  test  of  this  form  is  very  large  and  thick.  The  largest  specimens  measured  119  millimeters  in  diameter.  The 
outline  seen  from  above  is  circular  to  elliptical.  The  margins  are  swollen  and  the  summit  very  slightly  elevated. 
On  the  posterior  margin  is  a  faint  reentrant  angle  opposite  the  anal  opening.  The  petals  are  broad  and  nearly  closed 
at  the  extremity.  The  median  interporiferous  zones  are  broad,  while  the  outer  rows  of  pores  converge  at  the  ends 
so  as  almost  to  inclose  them.  The  tuberculation  is  uniform  on  both  the  upper  and  lower  surfaces  and  the  tubercles 
are  of  nearly  the  same  size  over  the  whole  test.  The  actinal  siKtace  is  strongly  concave  and  the  actinostome  deeply 
sunken.     The  ambulacral  furrows  are  very  deep  and  extend  from  the  actinostome  to  the  margin. 

Dimensions. — Maximum  width  100  millimeters;  maximum  length  119  millimeters;  maxi- 
mum thickness  37  millimeters. 

Related  forms. — Weaver  makes  the  following  remarks  on  related  forms: 

Clypeaster  bowersi  differs  considerably  from  the  other  members  of  this  genus  on  the  Pacific  coast.  It  is  not  tar 
removed  from  C.  breunigei  Laube,  which  occurs  in  the  Eocene  in  the  Lybian  Desert  of  Africa.  C.  bowersi  is  nearly 
twice  as  large  as  C.  breunigei  and  is  elUpsoidal  in  outline  with  thick  margins,  while  the  latter  is  pentagonal  and  has 
thin  margins.  The  upper  surface  of  the  former  is  only  slightly  arched,  while  the  apical  system  of  the  latter  is  conical 
and  then  gradually  slopes  to  the  margin.  They  differ  also  in  the  character  of  the  petals  and  in  the  position  of  the 
anal  pore.  In  C.  bmoersi  the  petals  are  broad  and  the  poriferous  zones  lie  nearly  parallel.  The  anus  is  situated  on 
the  actinal  surface  at  a  distance  from  the  margin  about  equal  to  its  diameter. 

Clypeaster  bowersi  shows  a  close  relationship  to  Diplothecanthus  rosaccus  (Lamarck).  It  differs  in  that  it  is  much 
flatter,  the  superior  surface  of  D.  rosaceus  being  more  strongly  convex.  The  actinostome  of  the  former  is  sunken  in  a 
cavity  which  narrows  gradually  and  is  of  much  greater  extent  than  in  D.  rosaceus.  In  D.  rosaceus  the  ambulacral 
areas  are  more  or  less  swollen  and  rise  above  the  general  level  of  the  test,  while  in  C  bowersi  they  are  nearly  at  the 
same  level  as  the  interambulacral  areas.  The  posterior  ambulacral  petals  are  the  longest  and  the  odd  ambulacral 
petal  is  the  shortest  in  D .  rosaceus.  In  C.  bowersi  the  odd  ambulacral  petal  is  the  longest  and  the  remaining  four  are  of 
equal  size. 

Locality. — Colorado  Desert  (Weaver).' 

Geologic  horizon. — Associated  with  a  fauna  presumed  to  be  of  Miocene  age  (Weaver).' 

Collection. — University  of  California. 

•  Since  the  above  description  was  written  William  S.  W.  Kew  has  published  some  additional  data  relative  to  C.  bowersi  based  on  new 
material  collected  by  him  (California  Univ.  Dept.  Geology  Bull.,  vol.  8,  No.  3,  p.  50,  Pis.  IV,  V,  1914).  He  supplements  Weaver's  description 
by  mentioning  that  there  are  faint  reentrant  angles  opposite  all  the  interambulacral  areas,  that  the  petals  are  obovate,  that  the  anterior  petal  is 
somewhat  raised,  and  that  the  periproct  is  large,  depressed,  and  inframarginal.  Kew  gives.several  new  localities,  all  being  near  Coyote  Moun- 
tain, Carrizo  Creek  region,  California.  He  also  says  that  C.  bowersi  occurs  at  all  the  localities,  in  his  lower  division  of  the  Carrizo  Creek  forma- 
tion, the  age  of  which  has  not  yet  been  definitely  determined.  Arnold,  in  1910  (Willis  and  Salisbury,  Outlines  of  geologic  history,  p.  245), 
regarded  the  Carrizo  Creek  beds  as  equivalent  to  the  Etchegoin  formation  which  is  now  thought  to  be  upper  Miocene  and  lower  Pliocene  (?). 


210  MESOZOIC   AKD    CEXOZOIC    ECHINODEBMATA    OF    THE    UNITED    STATES. 

Clypeaster?  breweeianus  (Remond). 

Plate  XCVI,  figures  2a-c,  3. 

Echinarachnius  brewerianus  Remond,  1863,  Califurnia  Acad.  Sci.  Proc,  vol.  3,  p.  53;  no  figure. 

Echinarachnius  brexverianus  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

Echinarachnius  brewerianus  Gabb,  1869,  Geol.  Survey  CaUfomia,  Paleontology,  vol.  2,  pp.  36,  109,  PI.  XII,  fig.  65,  65a. 

Echinarachnius  brewerianus  Cooper,  1888,  Cat.  California  fossils:  State  Mineralogist  Seventh  Rept.,  p.  271. 

Clypeaster  (?)  brewerianus  Merriam,  1899,  California  Acad.  Sci.  Proc,  3d  ser..  Geology,  vol.  1,  No.  5,  p.  166,  PL  XXI, 

fig.  2. 
Astrodapsis  brewerianus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  702. 

Determinative  characters. — Test  small,  subelliptical  to  subcircular  in  marginal  outline, 
faint]}'  notched  opposite  posterior  petals,  longer  than  broad.  The  whole  form  is  much  depressed; 
upper  surface  somewhat  convex,  flattened  near  center,  margin  rather  thick,  rounded;  apex 
central;  under  surface  flat  near  margin,  slightly  concave  near  center.  Ambulacral  petals  sub- 
equal,  plates  long  and  narrow,  poriferous  zones  divergmg  from  apical  region  to  near  margin, 
^vith  a  slight  constriction  about  two-thirds  the  way.  Apical  system  central.  Peristome 
probably  central.     Periproct  very  small,  subcircular,  inframarginal,  almost  marginal. 

Dimensions. — Specimen  A:  Length  32  millimeters;  width  28  millimeters;  height  9  milli- 
mieters.  Specimen  B;  length  36  millimeters;  width  31  millimeters;  height  12  millimeters. 
j,  Description. — This  species  was  described  but  not  figured  by  Remond  as  early  as  1863,  was 
first  figured  by  Gabb  in  1869;  and  was  redescribed  and  refigured  by  Merriam  in  1899.  The 
test  is  small,  rarely  exceeding  1|  inches  in  length.  In  marguial  outline  it  is  subelliptical  to 
subcircular,  faintly  notched  opposite  posterior  petals,  longer  than  broad.  The  whole  form  is 
considerably  depressed;  the  upper  surface  rising  in  gentle  convex  curves  from  the  moderately 
thick,  rounded  margin  to  a  flattened  area  near  the  centrally  located  apex;  the  under  surface 
flat  near  the  margin,  slightly  concave  toward  the  center. 

The  ambidacral  areas  are  wide,  wider  throughout  than  the  interambulacral  areas,  the 
plates  bemg  long  and  narrow  in  the  petaloid  region  and  just  at  the  margin;  the  dorsal  portions 
petaloid.  The  petals  aj-e  subequal  in  length,  sharply  pointed  near  the  apical  system,  widening 
rapidly  for  two-thirds  their  length,  then  narro^ong  slightly  and  again  widening  rapidly  to  their 
ends  where  they  are  wide  open.  Several  pairs  of  pores  continue  beyond  the  petals  proper, 
diverging  from  the  ends  of  the  petals  to  the  margin.  The  interporiferous  areas  are  very  wide, 
from  thi-ee  to  four  times  as  -wdde  as  the  poriferous  zones,  flush  or  slightly  tumid;  poriferous 
zones  very  narrow  near  apical  system,  rather  wide  near  ends  of  petals;  pores  oval,  pairs 
conjugated. 

The  interambulacral  areas  are  relatively  narrow,  very  narrow  near  the  apical  system. 
The  test  is  covered  with  small,  nearly  uniform  tubercles,  which  are  of  nearly  the  same  size  on 
the  upper  and  lower  surfaces. 

Tne  apical  system  is  central  and  coincident  with  the  apex.  The  details  can  rarely  be 
made  out  on  the  specimens. 

The  peristome  and  ambulacral  grooves  could  not  be  clearly  made  out  on  the  specimens 
studied.  One  fragment  examined  indicated  that  the  peristome  is  small,  central,  or  subcentral 
and  circular. 

The  periproct  is  very  small,  subcircular,  and  inframarginal,  almost  marginaL 

Related  forms. — This  species  does  not  appear  to  be  closely  related  to  any  other  American 
species.  It  resembles  Astrodapsis  turnidus  somewhat,  as  noted  by  Merriam,  but  lacks  the 
alternating  tumid  petals  and  depressed  interambulacral  areas  characteristic  of  that  species. 
Until  s])ecimens  showing  the  ambulacral  grooves  are  found  the  generic  position  can  not  be 
determined  with  certainty. 

Localities. — Near  Lafayette,  Concord  quadrangle;  2  miles  east  of  Walnut  Creek  House, 
Walnut  Creek,  Cal. 

Geologic  horizon. — "Upper  Contra  Costa  Miocene,"  probably  San  Pablo  formation,  upper 
Miocene. 

Collections. — University  of  California  (19423,  B);  Academy  of  Natural  Sciences  of  Philadel- 
phia (1088,  A). 


MIOCENE   ECHINODEKMATA.  211 

Cltpeaster?  gabbi  Remond. 

Clypeaster  gabbi  Remond,  1863,  California  Acad.  Sci.  Proc,  vol.  3,  pp.  53,  54,  no  figure. 
Chjpeastcr  gabbi  Meek,  1864,  Smithsonian  Jlisc.  Coll.,  vol.  7  (183),  p.  2. 

Clypeaster  gabbi  Gabb,  1869,  Geol.  Survey  California,  Paleontology,  vol.  2,  pp.  36,  109,  PI.  XII,  figs.  64,  64a. 
Clypeaster  gabbi  Cooper,  1888,  Catalogue  of  California  fossils:  State  Mineralogist  Seventh  Rept.,  p.  271. 
{"?)  Scutella  gabbi  Memam,18Q9,  California  Acad.  Sci.  Proc,  3d  ser.,  Geology,  vol.  1,  No.  5,  p.   168,  PI.  XXII, 
figs.  5,  5a. 

Description. — As  the  writer  has  been  unable  to  examine  any  specimens  which  can  be  posi- 
tively referred  to  this  species,  Remond's  description  is  given  verbatim: 

Disk  rather  small,  comparatively  thick,  varying  from  circular  to  subpentagonal  and  irregular  suboval.  Apex 
nearly  central,  subelevated;  margin  rounded;  genital  apparatus  subangular.  Ambulacral  star  almost  symmetrical; 
petals  about  equal  in  length,  elongated,  open  at  their  extremities.  Inferior  surface  flat  near  the  edge  and  gently 
concave  in  the  center.  Mouth  depressed,  subcentral.  Ambulacral  fmTows  straight,  slightly  marked.  Anal  aper- 
ture very  small,  marginal.  Tubercles  of  the  upper  sm-face  nimierous,  especially  in  the  ambulacra,  round  and 
prominent. 

Dimensions. — ^According  to  Remond  the  "  greatest  diameter  is  1.16  inches,  smallest  diame- 
ter 1.10  inches,  height  0.28  inch." 

Belated  forms . — As  Remond  imfortimately  failed  to  figure  his  form,  and  as  no  specimens 
answering  satisfactorily  to  his  description  are  available,  considerable  uncertainty  exists  regard- 
ing this  species  and  its  relations  to  other  Cahfornian  echinoids.  As  stated  in  the  discussion  of 
Scutella  gabbi  (Remond)  Merriam  (p.  189),  the  form  described  and  figured  by  Merriam  differs 
in  several  important  particulars  which  can  not  be  ignored,  and  this  renders  it  doubtful  whether 
Merriam  has  described  and  figured  identically  the  same  fonn  as  Remond.  Additional  collect- 
ing at  Remond's  locality  may  result  in  discovermg  specimens  answering  to  his  description, 
otherwise  the  species  must  remain  of  doubtful  character. 

Locality  and  geologic  liorizon. — According  to  Remond,  this  species  "  occurs  abundantly 
on  the  eastern  shore  of  San  Pablo  Bay,  south  of  Mare  Island,  Cal.,  in  soft  sandstones  of 
Miocene  age." 

Order  ATELOSTOMATA. 

Suborder  ASTERNATA. 

Family  CASSIDULID^. 

Genus  CASSIDTJLTJS  Lamarck. 
Cassidixlus  bassleri  Twitchell,  n.  sp. 

Plate  XCV,  figures  5a-d. 

Determinative  cJiaracters. — Test  small,  subovate  to  subcircular  in  marginal  outline,  broadest 
posteriorly;  upper  surface  convex,  somewhat  flattened  on  top,  sides  equally  dechning;  margin 
rounded  on  the  sides  and  anteriorly,  somewhat  angular  at  the  rostrated  posterior  end;  under- 
surface  concave  centrally.  Apex  central;  apical  system  excentric  anteriorly.  Ambulacral 
areas  rather  broad  in  petaloidal  dorsal  portions,  narrower  elsewhere;  poriferous  zones  broad, 
outer  row  of  pores  slitlike  or  elongate  elliptical.  Peristome  small,  central,  pentagonal  to  sub- 
stellate,  with  large  weU-defiiied  floscelle.  Periproct  oval,  situated  rather  high  above  the  margin, 
in  a  short  sulcus. 

Dimensions. — Length  28  miUimeters;  width  25  milUmeters;  height  14  millimeters. 

Description. — Specimens  of  this  species  have  been  known  for  some  years;  but  it  has  usually 
been  confused  with  the  Cretaceous  species  Cassidulus  sequoreus  Morton  and  so  labeled  in  the 
collections.  It  is  named  in  honor  of  Ray  S.  Bassler,  of  the  U.  S.  National  Museum.  The  test 
is  smaU,  rarely  exceeding  an  inch  in  diameter;  subovate  to  subcircular  in  marginal  outhne, 
usually  shghtly  broader  posteriorly  than  anteriorly  and  shghtly  longer  than  broad.  The  upper 
surface  is  moderately  elevated,  the  height  being  equal  to  about  half  the  diameter,  convex,  some- 
what flattened  on  top  from  above  the  periproct  to  the  apical  system,  equally  dechning  anteriorly 
and  on  the  sides,  posteriorly  it  slopes  from  above  the  periproct  to  the  margin  in  a  steep,  oblique. 


212  MESOZOIC    AND   CENOZOIC    ECHINODEKMATA    OF    THE    UNITED    STATES. 

nearly  straight  line;  margin  rounded  along  the  sides,  less  so  at  the  anterior  end,  somewhat 
angular  at  the  rostrated  posterior  end;  undersurface  flattened,  concave  centrally.  The  apex  is 
central  or  subcentral. 

The  ambulacral  areas  are  rather  broad  in  the  petaloid  dorsal  portions,  less  so  at  the  ambitus, 
and  narrow  at  the  ends  of  the  petals  and  actinaUy:  the  petals  are  relatively  large,  broad,  sub- 
equal  in  length,  extending  two-thirds  or  more  of  the  distance  to  the  ambitus;  the  poriferous 
zones  are  broad,  though  less  so  than  the  interporiferous  areas,  outer  row  of  pores  slithke  or 
elongate  eUiptical,  inner  row  round,  pairs  of  pores  conjugate. 

The  surface  of  the  test  is  closely  set  with  small  imperforate  tubercles  set  in  deep  scrobi- 
cules.  The  tubercles  increase  in  size  on  the  undersurface  except  along  a  median  band  which 
is  somewhat  smooth  but  dotted  with  numerous  granulations-. 

The  apical  system  is  excentric  anteriorly.  There  are  four  genital  pores,  the  anterior  pair 
being  nearer  together  than  the  posterior.  The  right  anterior  genital  plate,  which  is  modified 
to  form  the  madreporite,  is  very  large,  occupjTiig  the  larger  part  of  the  system.  There  are 
five  small  radial  plates,  each  perforated  by  a  small  pore. 

The  peristome  is  small,  central,  pentagonal  to  substellate,  with  a  large  floscelle  with  promi- 
nent bourrelets  and  well-defined,  broad,  oval  phyUodes. 

The  periproct  is  oval,  or  subelliptical,  longitudinally  elongate,  in  a  short  sulcus  situated 
rather  high  above  the  posterior  margin.  The  ends  of  the  posterior  petals  are  about  opposite  the 
middle  of  the  periproct. 

Related  forms . — This  species  is  similar  m  a  number  of  features  to  Cassidulus  ierryi,  but  it 
is  more  elevated,  has  a  more  rounded  margin  and  has  its  peristome  central  instead  of  anteriorly 
excentric.  It  also  presents  interesting  resemblances  to  the  Cretaceous  species  C.  sequoreus, 
and  C.  micrococcus,  but  can  be  separated  from  the  former  by  its  more  subcircular  marginal  out- 
line, its  central  peristome,  the  slightly  higher  position  of  its  periproct,  and  the  more  elongate 
character  of  the  outer  row  of  pores  of  its  petals,  and  from  the  latter  by  its  much  smaller  size, 
its  relatively  larger  floscelle,  and  the  somewhat  lower  position  of  its  periproct. 

Locality  and  geologic  horizon. — The  specimens  on  which  this  species  is  founded  are  said  to  be 
from  the  Miocene  of  North  CaroUna.     They  can  not  be  more  definitely  located. 

Collection. — U.  S.  National  Museum  (9476). 

Galerites  oregonensis  Dana. 

Gakrites  oregonends  Dana,  1849,  Repi,.  U.  S.  Expl.  Exped.,  Geology,  vol.  10,  p.  729,  PI.  II,  figs.  5,  6,  6a. 
Galerites  oregonensis  Gabb,  1869,  Geol.  Survey  of  California,  Paleontology,  vol.  2,  p.  123. 

TMs  species  was  based  by  J.  D.  Dana  on  a  few  fragments  and  spines  obtained  from  the 
argillaceous  Astoria  shale  of  the  lower  Miocene  of  Oregon.  The  spines  are  said  to  be  "half  an 
inch  long,  very  slender,  delicately  striate,  with  the  striae  punctate  or  subcrenulate."  No  descrip- 
tion of  the  test  is  given  and  Dana  himself  said  the  "specimens  are  so  imperfect  that  we  refer  it 
with  hesitation  to  the  genus  Galerites."  In  view  of  the  imperfect  character  of  the  specimens, 
the  acceptance  of  the  species  is  reserved  until  additional  material  has  been  obtained. 

Suborder  STERNATA. 
FamUy  SPATANGID^. 

Genus  AGASSIZIA  Valentin. 

Agassizia  poritera  (Ravenel). 

Plate  XCVII,  figures  la-d. 

Brissopsis  poriferus  Ravenel,  1848,  Echinidas,  recent  and  fossil,  South  Carolina,  p.  4,  PI.  II,  figs.  5,  6. 

-Brmopsi's  pofi/erus  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 

Agassizia  porifera  McCrady,  1857,  Pliocene  fossils,  South  Carolina,  pp.  5,  6,  PI.  I,  fig.  5,  PI.  II,  fig.  4. 

Agassizia  'porifera  Meek,  1864,  Check  list,  Miocene,  p.  2. 

(?)  Agassizia  excentrica  A.  Agassiz,  1872,  Revision  of  the  Echini,  pt.  1,  p.  88. 

Agassizia  porifera  A.  Agassiz,  1874,  Revision  of  the  Echini,  pt.  4,  p.  751.  i 

Agassizia  porifera  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 


MIOCENE   ECHINODEEMATA.  213 

Determinative  characters. — Test  moderate,  ovoid,  tall,  apex  slightly  excentric  forward,  no 
anterior  groove,  nearly  flat  below.  Ambulacra  narrow,  paired  in  shallow  grooves,  antero- 
lateral much  longer  than  the  posterolateral;  pairs  small,  sUtlike.  Interambulacra  broad, 
covered  with  very  small  tubercles.     Fascicles  indistinct.     Peristome  near  forward  margin. 

Dimensions. — Length  42  miUimeters;  width  .37  millimeters;  height  .35  milhmeters. 

Description. — Tliis  species  was  figured  by  Ravenel  in  1848,  and  described  and  figured  by 
McCrady  in  1858.  The  test  is  of  moderate  size,  ovoid,  and  tall.  The  apex  is  slightly  excentric 
forward.  There  is  no  anterior  groove,  a  slight  depression  extending  from  the  apex  part  way 
to  the  margin.     The  lower  surface  is  nearly  flat. 

The  ambulacra  are  narrow,  the  j^osterolateral  pair  bent  outward  toward  the  margin.  The 
anterolateral  nearly  straight.  The  paired  ambulacra  in  shallow  depressions,  long,  open  below, 
the  posterolateral  shorter  than  the  anterolateral  pair. 

The  interambulacra  are  wide,  the  paired  interambulacra  sUghtty  gibbous  at  their  upper 
ends.     Portions  of  the  peripetalous  and  lateral  fascioles  are  rather  inchstinctly  shown. 

The  peristome  is  near  the  anterior  margin  with  a  well-developed  labrum.  The  periproct 
is  not  shown  on  the  single  specimen  of  tliis  species  studied. 

Locality. — Near  Oakle}'  Inlet,  Waccamaw,  S.  C. 

Geologic  Jtorizon. — iliocene. 

Collection. — American  Museum  of  Natural  History. 

Genus  ECHINOCARDITJM  Gray. 

ECHINOCARDIUM    ORTHONOTUM    Courad. 

Plate  XCVII,  figs.  2a-c;  Plate  XCVIII,  figs,  la-c,  2a-c. 

Spatangus  orthonotus  Conrad,  1843,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  1,  p.  327. 

Amphidetus  virginianus  Forbes,  1845,  Geol.  Soc.  London  Quart.  Jour.,  vol.  1,  pp.  425,  426,  3  figs. 

Amphidetiis  virginianus  Forbes,  1846,  Geol.  Soc.  London  Proc,  vol.  6,  pp.  559,  560,  3  figs. 

Amphidetus  orthonotus  Tuomey  and  Holmes,  1855,  Pliocene  fossils,  South  Carolina,  pp.  6,  7,  figs.  1,  la-c. 

Amphidetus  virginianus  Emmons,  1858,  North  Carolina  Geol.  Survey  Kept.,  p.  310,  fig.  245a-c. 

Echinocardium  virginianum  Desor,  1858,  Synopsis  echinides  fossiles,  p.  408. 

Echinocardium  orthonotus  Conrad,  1805,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  17,  p.  75. 

(?)  Echinocardium  pennatijidum  A.  Agassiz,  1872,  Revision  of  the  Echini,  pt.  1,  p.  111. 

Echinocardium  orthonotum  A.  Agassiz,  1874,  Revision  of  the  Echini,  pt.  4,  p.  751. 

Amphidetus  virginianus  Schluter,  1899,  Deutsche  Geol.  Gesell.  Zeitschr.,  vol.  51,  p.  113. 

Echinocardium  orthonotum  Clark,  1904,  Maryland  Geol.  Survey,  Miocene,  pp.  430^132,  PI.  CXIX,  figs.  la-c. 

Echinocardium  orthonotum  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  706. 

Determinative  characters. — Test  large,  ovate  to  cordiform,  elevated,  upper  surface  nearly 
flat  forward,  deep  and  broad,  anterior  groove  higher  posteriorly  with  truncated  surface,  tumid 
plastron  below.  Ambidacra  wide,  anterior  in  broad  groove,  paired  ambulacra  in  shallow 
grooves  triangular  in  outline,  widely  open  above,  narrow  below;  pore  pairs  large  and  not  numer- 
ous. Interambulacra  narrow  above,  mde  below;  fascioles  distinct.  Peristome  large,  slitlike. 
Periproct  high  on  posterior  truncation. 

Dimensions. — Specimen  A:  Length  58  millimeters;  width  52  milhmeters;  height  29  milh- 
meters.    Specimen  B:  Length  51  millimeters;  width  46  milhmeters;  height  29  millimeters. 

Description. — This  species  was  first  described  by  Conrad  in  1843,  but  not  figiu"ed.  Forbes, 
in  1845,  redescribed  and  figured  the  form  luuler  the  name  of  Amphidetus  virginianus.  The 
test  is  rather  large,  irregularly  ovate  to  cordiform,  elevated  but  more  posteriorly  than  anteriorly. 
The  upper  surface  is  mostly  flat  forward.  A  broad  and  rather  deep  anterior  groove  with  shghtly 
gibbous  edges  indents  the  upper  surface  but  narrows  and  shallows  toward  the  margin.  The 
posterior  portion  is  elevated  into  a  broad  ridge  which  continues  nearly  to  the  truncated  posterior 
margin.     The  lower  surface  is  nearly  flat  except  for  the  elevated  plastron. 

The  ambulacra  are  wide,  the  anterior  being  situated  in  the  broad  anterior  groove.  The 
paired  ambulacra  are  situated  in  shallow  grooves  on  the  upper  surface.  They  are  triangular 
in  outhne,  widely  open  above  and  narrow  below,  the  anterolateral  being  wider  above   than  the 


214  MESOZOIC   AND   CENOZOIC   ECHINODEEMATA   OF    THE   UNITED   STATES. 

posterolateral.  The  pore  pairs  are  large  and  not  numerous.  They  appear  again  on  the  lower 
surface  near  the  peristome. 

The  interambulacra  are  narrow  above  and  widen  rapidly.  They  have  numerous  large 
tubercles  below  which  become  few  and  irregularly  scattered  above  the  lower  margin.  The 
fasciole  can  be  plainly  traced. 

The  apical  system  is  small.  The  peristome  is  large  and  shtlike,  ver}^  much  elongated 
transversely.     The  periproct  is  moderate  in  size,  high  on  the  posterior  truncation. 

Locality. — James  River,  Ya. 

Geologic  horizon. — Yorktown  formation,  upper  Miocene. 

Collections. — Academy  of  Natural  Sciences  of  PMladelpliia  (1079);  American  Museum  of 
Natural  History;  U.  S.  National  Museum;  Johns  Hopkins  University  (T.  1002). 

ECHINOCAEDIUM    DEPEESSUM    Clark,  U.  Sp. 
Plate  XCVIII,  figures  3a-c. 

Determinative  characters. — Test  moderate,  cordiform,  low,  depressed,  both  upper  and 
lower  surfaces  nearly  fiat,  anterior  groove  shallow,  posterior  truncation.  Ambulacra  wide, 
anterior  in  shallow  groove,  paired  in  grooves,  triangular  in  outline,  open  above,  narrow  below. 
Interambulacra  narrow  above,  widening  rapidly  toward  the  ambitus.     Peristome  small. 

Dimensions. — length  40  millimeters;  width  37  millimeters;  height  13  milhmeters. 

Description. — This  species  is  represented  only  by  casts,  which,  however,  are  very  different 
in  their  characters  from  E.  orthonotum ,  the  only  other  Miocene  representative  of  tliis  genus  from 
American  deposits.  Tlie  test  is  of  moderate  size,  cordiform,  low,  much  depressed,  nearly  flat. 
Tlie  anterior  groove  is  shallow  and  broad-     The  posterior  margin  is  truncated. 

The  ambulacra  are  wide,  the  paired  ambulacra  being  situated  in  shallow  grooves  triangular 
in  outline.  They  are  open  above  and  narrow  below.  The  interambulacra  are  narrow  above, 
forming  a  very  obtuse  angle,  but  Madening  rapidly  below  toward  the  ambitus.  The  fascioles 
are  absent.     The  peristome  is  small  and  apparently  transversely  elongated. 

Locality. — Near  old  Chattahoochee  Landing,  Apalachicola  River,  Fla. 

Geologic  horizon. — Lower  Miocene. 

Collection. — U.  S.  National  Museum  (164454). 

EcHiNOCAKDiuM  GOTHicus  (Ravcuel). 

Amphidetus  gothicus  Ravenel,  1848,  Eclunidse,  recent  and  fossil,  South  Carolina,  p.  4  and  figure. 
Amphidetus  mnpUphorus  McCrady,  1855,  Pliocene  fossils,  South  Carolina,  pp.  7,  8,  PI.  11,  fig.  2. 
Amphidetus  gothicus  McCrady,  1855,  Pliocene  fossils,  South  Carolina,  pp.  7,  8,  PI.  II,  fig.  3. 
(?)  Echinocardium  cordatiim  A.  Agassiz,  1872,  Revision  of  the  Ecliini,  pt.  1,  pp.  109,  110. 
Amphidetus  gothicus  A.  Agassiz,  1874,  Revision  of  the  Ecliini,  pt.  4,  p.  751. 
Echinocardium  ampliflorus.  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 
Echinocardium  gothicum  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Description. — No  material  has  been  secured  and  it  is  therefore  impossible  to  satisfactorily 
describe  this  species.  A.  Agassiz  regards  E.  gothicus  and  E.  ampliphorus  as  the  same  species 
and  refers  it  doubtfully  to  E.  cordatum,  which  is  found  widely  distributed  in  the  Atlantic  Ocean 
to-day. 

Locality. — Tlie  Grove,  Cooper  River,  S.  C. 

Geologic  horizon. — Duplin  marl,  upper  iliocene. 

Collection. . — LTnkno\^^l . 

Genus  LINTHIA  Merian. 

■  LiNTHLA?  CALiFORNicA  Weaver. 

Plate  XCVIII,  figure  4. 

Linthia  (?)  californica  Weaver,  1908,  Univ.  California  Dept.  Geology  Bull.,  vol.  5,  No.  17,  pp.  272,  274,  PI.  XXI,  fig.  2. 
Brissopsis  californica  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  705. 


MIOCENE   ECHINODEKMATA.  215 

Description. — Weaver  says : 

The  outline  of  the  test  from  above  is  elliptical.  The  anterior  groove  is  deep.  The  apical  system  is  small  and 
situated  slightly  anterior  to  the  center.  The  central  portion  of  the  lateral  interambulacral  plates  forms  a  series  of 
irregular  ridges  extending  from  the  apical  system  to  the  margin.  The  posterior  interambulacral  area  is  elevated.  The 
three  anterior  ambulacra  are  nearly  equal  in  size  and  larger  than  the  posterior  areas  as  far  as  kno^vn.  The  poriferous 
zones  of  the  ambulacra  are  narrow,  but  the  pores  are  large.  The  specimen  is  a  poorly  preserved  cast  and  further  data 
are  lacking.  Tliis  sjsecies  has  been  referred  to  Lintliia  rather  than  to  Schizaster  on  account  of  the  more  central  position 
of  the  apical  system. 

Dimensions. — Length  19  millimeters;  width  14  millim.eters ;  height  7  millimeters. 
Locality. — One  mile  west  of  Bear  Valley,  Contra  Costa  County,  Cal. 
Geologic  horizon. — Lowest  member  of  the  Monterey  shale,  middle  Miocene. 
Collection. — University  of  California. 

Genus  BRISSUS  Leske. 

Brissus  spatiosus  (Ravenel). 

Pericosmus  spatiosus  Ravenel,  1848,  Ecliinidfe,  recent  and  fossil.  South  Carolina,  p.  4. 

Heminster  (Pcricosmos)  spatiosus  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  p.  160. 

Brissus  spatiosus  McCrady,  1855,  Pliocene  fossils.  South  Carolina,  p.  8,  PL  III,  figs.  1,  la-c. 

Brissus  spatiosus  Meek,  1864,  Check  list,  Miocene,  p.  2. 

Meoma  ventricosa  A.  Agassiz,  1872,  Revision  of  the  Echini,  pt.  1,  p.  143. 

Meoma  spatiosa  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Description. — This  species,  which  was  named  by  Ravenel,  was  subsequently  figured  and 
described  by  McCrady.  It  is  regarded  by  A.  Agassiz  as  a  synonym  of  Meoma  ventricosa.  No 
specimens  have  been  found  for  the  present  study,  and  in  the  absence  of  material  it  is  difficult  to 
determine  the  true  relations  of  the  species,  althougli  it  may  well  belong  to  the  genus  Meoma. 

Locality. — Tlie  Grove,  Cooper  River,  S.  C. 

Geologic  horizon. — Duphn  marl,  upper  Miocene. 

Collection. — Unkno-\vn. 

Genus  METALIA  Gray. 

Metalia  eaveneliana  (McCrady). 

Plagionotusravenelianus  McCTudy,  1855,  Pliocene  fossils.  South  Carolina,  pp.  10,  11,  PI.  Ill,  figs.  3,  3a. 

Plagionotis  ravenelianus  Meek,  1864,  Check  list,  Miocene,  p.  2. 

Plagionotus  ravenelianus  A.  Agassiz,  1874,  Revision  of  the  Ecliini,  pt.  4,  p.  751. 

Plagiobrissus  ravenelianus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Description. — No  material  has  been  secured  and  it  is  therefore  impossible  to  satisfactorily 
describe  tliis  species.     The  genus  Plagionotus  is  now  regarded  as  a  synonym  of  Metalia. 
Locality. — The  Grove,  Cooper  River,  S.  C. 
Geologic  horizon. — Duplin  marl,  upper  Miocene. 
Collection. — Unknown. 

Metalia  holmesi  (McCradj^). 

Plagionotus  holmesii  McCrady,  1855,  Pliocene  fossils.  South  Carolina,  pp.  9,  10,  PL  III,  figs.  2,  2a. 

Plagionotus  holmesii  Meek,  1864,  Check  list,  Miocene,  p.  2. 

Plagionotus  holmesii  A.  Agassiz,  1874,  Revision  of  the  Echini,  pt.  4,  p.  751. 

Plagiobrissus  holmesi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Description. — No  material  has  been  secured  and  it  is  therefore  impossible  to  satisfactorily 
describe  this  species.     The  genus  Plagionotus  is  now  regarded  as  a  synonym  of  Metalia. 
Locality. — Goose  Creek,  S.  C. 
Geologic  Jiorizon. — Duplin  marl,  ujJiDer  Miocene. 
Collection. — Unknown. 


PLIOCENE  ECHINODERMATA. 

Qass  EC'HINOIDEA. 

Subclass  REGULAEIA  ECTOBRANCHIATA. 

Order  DIADEMOIDEA. 

Suborder  ECHININA. 

Family  STRONGTLOCENTROTID^. 

Genus  STBONGYLOCENTBOTUS  Brandt. 

•  Strongylocentkotus  drobachiensis  (Miiller). 

Plate  XCIX,  figures  la-c. 

Description. — Two  specimens  have  been  examined  from  the  PUoccne  beds  of  Caloosahatchie 
River  that  evidently  belong  to  this  common  and  widespread  Recent  species.  The  characters  are 
similar  to  those  of  hving  forms,  and  it  seems  therefore  that  the  specimens  must  be  regarded  as 
representing  the  same  species.  A.  Agassiz'  points  out  the  great  variability  in  the  different 
individuals  of  the  species,  forms  much  more  extreme  than  those  of  the  two  Pliocene  specimens 
studied  occurring. 

Dimensions. — Diameter  55  millimeters;  height  27  millimeters. 

Locality. — Caloosahatchie  River,  Fla. 

Geologic  horizon. — Pliocene. 

Collection. — Wagner  Free  Institute  of  Science  (4350). 

Subclass  IRREGULARIA. 

Order  GNATHOSTOMATA. 

Suborder  CliYPEASTRINA. 

Family  SCUTELLID.E. 

Genus  DENDRASTER  Agassiz. 

Dendraster  iNTERLiNEATUs  (Stimpson). 

Plate  C,  figures  2a-b. 

Scutella  interlineata  Stimpson,  1856,  Pacific  Kailroad  Repts.,  vol.  5,  pp.  153,  154.  PI.  IV,  fig.  30. 

S cutella  interlineata 'Remond,  1863,  California  Acad.  Nat.  Sci.  Proc,  vol.  3,  pp.  14,  15. 

Scutella  interlineata  (Blake)  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

Scutella  interlineata  Gabb,  1869,  Geol.  Survey  California  Kept.,  Paleontology,  vol.  2,  p.  110. 

Scutella  interlineata  Cooper,  1888,  Cat.  California  fossils:   State  Mineralogist  Seventh  Rept.,  p.  271. 

Scutella  interlineata  Merriani,  1899,  California  Acad.  Nat.  Sci.  Proc,  3d  ser..  Geology,  vol.  1,  No.  5,  p.  169,  PI.  XXII, 

fig.  6. 
Dendraster  (?)  interlineatus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  706. 

Description  and  determinative  characters. — The  writer  has  been  unable  to  secure  for  study 
more  than  a  few  specimens  of  this  species.  Among  these  is  Stimpson's  type — a  greatly  weath- 
ered and  fragmentary  specimen.  As  Merriam,  on  the  other  hand,  has  had  considerable  material 
to  work  with,  his  description  is  here  repeated: 

Test  pentagonal  to  circular,  angular  or  truncated  posteriorly,  somewhat  arched  above;  summit  nearly  central  and 
in  front  of  the  excentric  apical  system,  specimens  ranging  up  to  over  120  millimeters  in  diameter. 

1  Revision  of  the  Echini,  pp.  2T7-2S1. 
21C 


PLIOCENE   ECHINODEKMATA.  217 

Ambulaci'a  rather  broad,  of  unequal  length,  anterior  three  of  about  the  same  length  and  longer  tl>an  the  posterior 
pair.  Anterior  petal  open  at  the  end,  the  others  nearly  closed.  Few  if  any  pores  continuing  beyond  the  ends  of  the 
petals. 

The  distance  fi-om  the  excentric  apical  system  to  the  posterior  margin  is  to  the  distance  to  the  anterior  margin  as 
1  to  1.5.  The  anus  is  supramarginal,  being  separated  from  the  margin  in  adult  specimens  by  about  the  width  of  one 
of  the  marginal  interambulacral  plates. 

No  specimens  have  been  seen  by  the  writer  in  which  the  ambulacral  furrows  are  well  shown.  On  such  specimens 
as  show  the  lower  side,  the  furrows  seem  to  be  dichotomously  divided  near  the  mouth.  This  agrees  with  Remond's 
description,  which  also  states  that  the  furrows  are  not  as  well  marked  nor  as  much  branched  as  in  Dendraster  excentricus. 

The  spines  of  the  upper  surface  are  about  1  millimeter  long;  they  are  longitudinally  striated  and  at  the  distal 
end  are  strongly  swollen  and  obliquely  truncated  or  bent.  The  spines  of  the  lower  surface  are  slender  striated  rods 
about  2  to  3  millimetei-s  long.     The  tubercles  differ  little  in  size  on  the  upper  and  lower  surfaces. 

The  internal  skeleton  comprises  numerous  in-egular  pillars  and  plates  near  the  margin  and  a  pair  of  radial  plates  in 
each  interambulacral  space. 

Dimensions. — The  specimens  vary  from  small  to  large,  ranging,  according  to  MeiTiam,  up 
to  120  millimeters  in  diameter.  The  specimen  figured  gave:  Length  56  millimeters;  width  56 
milUmetei's ;  height  5  millimeters. 

Belated  forms. — D.  interlineatus  is  very  closely  related  to  D.  oregonensis.  There  appear  to 
be  differences,  however,  which  justify  the  separation  of  the  two  forms,  to  judge  from  the  speci- 
mens studied.  D.  oregonensis  is  to  be  distinguished  by  the  details  of  its  ambulacral  petals.  In 
both  the  anterior  and  posterior  paired  petals  the  posterior  poriferous  zones  are  straight,  while  in 
D.  interlineatus  all  are  curving,  or  at  most  only  the  posterior  zones  of  the  posterior  pair  become 
nearly  straight.  In  D.  oregonensis  all  of  the  petals  are  weU  open  at  the  ends,  the  poriferous  zones 
converging  shghtly  or  not  at  all  toward  the  ends  and  diverging  sharply  at  the  ends,  with  several 
pairs  of  pores  occurring  between  the  ends  of  the  petals  and  the  margin;  while  one  of  the  most 
striking  characters  of  D.  interlineatus  is  the  curving  around  abruptly  toward  each  other  of  the 
poriferous  zones  so  as  to  practically  close  the  petals  in  all  but  the  anterior  petal .  D.  oregonensis 
differs  further  in  having  less  symmetrically  subelUptical  petals,  in  being  relatively  higher  in 
proportion  to  its  width,  and  in  ha\ang  a  relatively  larger  periproct. 

D.  interlineatus  also  resembles  S .  fairhanlcsi  and  S.  gahhi;  but  both  of  these  forms  can  be 
easily  distinguished  by  the  central  or  sUghtly  anteriorly  excentric  position  of  their  apical  systems, 
their  relatively  smaller  and  more  equal  petals,  and  their  wider  marginal  areas. 

Locality. — In  the  sea  cliffs  about  one-fourth  mile  above  Mussel  Rock  (figured  specimen) ; 
south  of  Point  Lobos,  near  San  Francisco  (type) ;  Ano  Nuevo  Creek,  near  Felt  Lake  aiid  in  the 
sea  chffs  between  Santa  Cruz  and  Capitola,  and  at  Rio  Dell  DiUer,  Cal.  (Arnold). 

Geologic  horizon. — Merced  formation,  upper  Pliocene. 

Collections. — U.  S.  National  Museum;  University  of  California  (19427). 

Genus  ASTRODAPSIS  Conrad. 
ASTRODAPSIS  FERNANDOENSIS  Pack. 

Plate  CI,  figures  1,2. 

Astrodapsis fernandoensis  Pack,  1909,  California  Univ.  Dept.  Geology  Bull.,  vol.  5,  No.  18,  p.  279,  PI.  XXIV,  figs.  3,  4. 
Astrodapsis  fernandoensis  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  706. 

Description. — As  the  writer  has  had  no  opportunity  to  study  any  specimens  of  this  species, 
the  description  of  Pack  will  be  given  in  full. 

Test  small;  suboval  in  outline,  anterior  end  rounded,  posterior  end  slightly  pointed;  much  depressed,  upper 
surface  very  slightly  convex,  apex  central;  edges  rounded.  Apical  system  central;  petals  extend  to  margin,  wide 
open  at  the  end,  raised  near  the  apical  system  but  almost  flush  with  the  surface  of  the  test  near  the  margin.  Poriferous 
zones  very  narrow,  together  forming  about  one-fourth  the  \vidth  of  the  petal.  The  two  posterior  petals  are  gently 
convex  toward  the  median  line  through  the  posterior  interambulacral  space.  A  broad,  shallow  depression  occupies 
the  center  of  the  interambulacral  areas;  the  two  secondary  depressions  so  prominent  in  Astrodapsis  antiselli  are  almo.st 
entirely  lacking.  Actinal  surface  gently  concave,  furrows  poorly  marked,  but  apparently  branched  as  in  Astrodapsis 
antiselli.  Anal  pore  submarginal,  large,  and  oval  in  outline.  The  posterior  end  of  the  test  is  jM-oduced  beyond  the  pore 
to  a  small  point,  particularly  noticeable  in  the  smaller  specimens.  Tubercles  very  large,  and  set  in  well-defined  pits 
apparently  the  same  on  upper  and  lower  surfaces. 


218  MESOZOIC   AND   CENOZOIC   ECHINODEKMATA   OF   THE   UNITED   STATES. 

Dimensions. — Length  51  millimeters;  width  39  millimeters;  height  8  millimeters. 

Related  forms. — Judging  from  Pack's  figures  and  description  A.  fernandoensis  is  very  closely 
allied  to  A.  antiselli  Conrad,  the  most  notable  points  of  resemblance  being  the  oval  outline,  the 
slight  pointing  of  the  posterior  end,  the  rounded  edges  and  the  slight  convexity  of  the  upper 
surface.  The  points  of  resemblance  are  so  striking  as  to  raise  the  question,  whether  A.  fernando- 
ensis ought  not  to  be  regarded  as  a  synonym  of  A.  antiselli;  but  as  Pack  does  not  state  that  the 
margin  of  A.  fernandoensis  is  very  thick  and  as  the  figures  suggest  a  greater  contrast  between 
the  elevation  of  its  ambulacral  ridges  and  the  depth  of  its  interambulacral  depressions  than 
occm's  in  A.  antiselli,  decision  is  reserved  until  authentic  specimens  of  Pack's  form  can  be 
examined. 

Locality. — Elsemere  Canyon,  Los  Angeles  County,  Cal. 

Geologic  horizon. — Fernando  formation,  lower  Pliocene  beds. 

Collection. — University  of  California  (A,  B). 

Family  CLYPEASTRID.t:. 

Genus  DIPLOTHECANTHTJS  Duncan. 
DiPLOTHECANTHUS  DALLi  Twitchell,  n.  sp. 
Plate  XCIX,  figures  2a-b;  Plate  C,  figures  la-b. 

Determinative  characters. — Test  large;  pentagonal  in  marginal  outline,  longer  than  broad, 
broadest  opposite  the  ends  of  the  anterior  petals,  pointed  anteriorly,  posterior  end  truncated 
centrally;  upper  surface  irregularly  convex,  high,  highest  back  of  center,  whence  sloping  gently 
and  in  a  straight  line  to  the  blunt,  tumid  anterior  edge  and  quite  steeply  and  in  a  straight  line  to 
the  thinner,  wedge-shaped  posterior  etlge ;  inider  surface  deeply  concave,  the  concavity  beginning 
near  the  margin  and  increasing  at  first  gradually  then  rapidly  to  the  center.  Ambulacral  petals 
large,  broad,  very  tumid,  almost  reaching  the  margin,  nearly  closing,  the  posterior  pair  slightly 
longer  than  the  odd  petal  which  is  slightly  longer  than  the  anterior  pair.  Apical  system  central, 
sloping  downward  anteriorly;  five  genital  pores  a  short  distance  from  the  slightly  depressed 
madreporite.  Peristome  large,  slightly  excentric  posteriorly,  subpentagonal,  deeply  sunken ; 
ambulacral  furrows  simple,  straight,  reaching  the  margin.  Periproct  rather  large,  subcircular; 
inframarginal,  almost  marginal. 

Dimensions. — Length  112  millimeters;  width  92  millimeters;  height  50  miUkneters. 

Description. — Only  a  few  specimens  of  this  handsome  clypeastroid  form  have  been  dis- 
covered. The  test  is  large;  pentagonal  in  marginal  outline,  the  corners  of  the  pentagon  being 
rounded  and  the  sides  straight  or  faintly  concave;  longer  than  broad,  broadest  opposite  the  ends 
of  the  anterior  petals,  pointed  anteriorly,  posterior  end  truncated  centrally;  margin  very  thick 
and  rounded  opposite  the  petals,  thinner  between  them,  thinnest  along  the  wedge-shaped  pos- 
terior edge.  'The  upper  surface  is  irregularly  convex,  high,  relatively  higher  than  in  other 
American  clypeastroid  forms.  The  apex  is  slightly  excentric  posteriorly,  being  located  at  the 
posterior  part  of  the  apical  system  from  which  point  the  upper  surface  slopes  gently  (the  angle 
being  about  30°  from  the  horizontal) ,  and  in  a  straight  line  to  the  wedge-shaped  posterior  margin. 
The  outline  along  a  longitudinal  median  section  is  therefore  angular  at  the  apex.  The  under 
surface  is  strongly  concave;  the  concavity  beginning  near  the  margin  and  increasing  gradually 
for  about  half  the  way,  then  very  rapidly  for  the  rest  of  the  way  to  the  deeply  sunken  peristome, 
where  it  is  about  one-half  the  height  of  the  test.  The  rapid  increase  in  the  concavity  begins 
somewhat  farther  from  the  anterior  end  than  it  does  elsewhere. 

The  ambulacral  areas  are  wide,  the  dorsal  portions  petaloid.  The  petals  are  very  large  and 
conspicuous,  broad,  very  tumid,  almost  reaching  the  margin,  nearly  closed  at  the  ends,  the  pos- 
terior pair  slightly  longer  than  the  otld  petal  which  is  slightly  longer  than  the  anterior  pair.  The 
poriferous  zones  are  wide,  narrowing  and  converging  rapidly  at  the  ends  so  as  to  almost  com- 
pletely inclose  the  interporiferous  area,  the  inner  row  of  pores  notably  higher  than  the  outer  row; 
pores  round,  subequal,  pairs  of  pores  conjugated.  The  interporiferous  areas  are  very  wide,  very 
tumid,  the  inner  portions  uniting  to  form  a  narrow  tumid  ring  around  the  madreporite. 


PLIOCENE   ECHINODEEMATA.  219 

The  interambulacral  areas  are  narrow  throughout  their  whole  length,  though  wider  between 
the  ends  of  the  petals  than  elsewhere,  much  narrower  than  the  ambulacral  areas.  The  whole 
surface  of  the  test  is  thickly  set  with  small  tubercles  which  are  somewhat  larger  on  the  under 
surface. 

The  apical  system  is  central,  sloping  downward  anteriorly  from  the  apex ;  the  madreporite 
large,  pentagonal,  slightly  depressed.  There  are  five  genital  pores  situated  a  short  distance 
from  the  madreporite;  and  there  are  five  small  radial  plates  at  the  edge  of  the  madreporite,  per- 
forated by  minute  pores. 

The  peristome  is  large,  subpentagonal,  slightly  excentric  posteriorly  at  the  deepest  point 
of  the  deep  concavity  on  the  under  surface.  The  ambulacral  furrows  are  simple,  straight 
shallow  grooves  extending  from  the  peristome  almost  to  the  margin,  which  are  deeper  midway 
than  toward  the  peristome. 

The  periproet  is  rather  large,  circular,  inframarginal,  almost  marginal. 

Related  forms. — B.  (?aZZi  is  very  closely  related  to  the  recent  American  form  generally  known 
as  Echinanihus  rosaceus  (which,  if  Duncan  be  followed,  sliould  be  Diplothecanthus  rosaceus), 
differing  from  it  chiefly  in  being. relatively  higher,  in  having  tlie  apex  slightly  excentric  posteriorly 
and  angular,  with  a  straighter  slope  anteriorly  and  a  steeper  slope  posteriorly,  in  having  the 
apical  system  sloping  downward  anteriorly,  and  in  having  tlie  interporiferous  areas  more  tumid 
and  coalescing  around  the  madreporite.  D.  dalli  rather  closely  resembles  in  many  features  the 
foreign  forms  Clypeaster  crassicostatus '  Agassiz,  from  the  Miocene  of  Austria-Hungary,  Italy, 
and  Corsica,  but  differe  from  it  in  being  less  elongate  longitudinall}'  and  more  elevated,  in  hav- 
ing more  difference  between  its  anterior  and  posterior  slope,  and  in  having  its  petals  broader, 
slightly  less  open  and  somewhat  longer. 

Locality. — Near  Fort  Thompson,  Caloosahatchee  River,  Fla. 

Geologic  horizon. — Caloosahatchee  marl,  PUocene. 

Collection.— U.  S.  National  Museum  (164670).  Collected  by  W.  H.  Dall,  after  whom  the 
species  is  named. 

Diplothecanthus  rosaceus  (Lamarck). 

Plate  CXI,  figures  la-b;  Plate  CIII,  figures  la-b 

Echinus  retindatus  Linne,  1758,  Systema  naturse,  p.  3191. 

Clypeaster  rosaceus  Lamarck,  1840,  Animaux  sans  vertfebres,  2d  ed.,  p.  289. 

Echinanthus  rosaceus  A.  Agassiz,  1872,  Revision  of  the  Echini,  pp.  106,  311,  514. 

Description. — This  well-known  recent  species  is  so  fully  described  elsewhere  it  is  needless 
to  give  a  detailed  description  here.  The  specimen  here  figured  was  reported  as  found  in  the 
Pliocene  deposits  of  Florida.  The  test  is  very  large;  pentagonal  in  marginal  outline,  the  corners 
of  the  pentagon  being  rounded  and  the  sides  and  posterior  end  slightly  concave;  somewhat 
longer  than  broad,  pointed  anteriorly;  margin  thick  and  rounded  opposite  the  petals,  less  so 
between  them.  The  upper  surface  is  convex,  moderatelj^  high,  of  uniform  height  at  the  highest 
parts  of  each  of  the  petals.  The  apex  is  central,  coincident  with  the  apical  system,  and  the 
upper  surface  is  nearly  level  for  nearlj'  an  inch  out  from  the  center  in  rather  steep  curves  along 
the  ambulacral  areas  and  in  steep  nearly  straight  fines  along  the  interambulacral  areas  to  the 
margin.  The  outline  along  a  longitudinal  median  section  is  nearly  level  for  the  central  third 
of  the  length  of  the  test  whence  it  slopes  nearly  equaUy  to  each  end.  The  under  surface  is 
nearly  flat  around  the  margin  and  rather  strongly  concave  around  the  peristome,  where  it  is 
less  than  one-half  the  height  of  the  test. 

The  ambulacral  areas  are  very  wide,  the  dorsal  portions  petaloid.  The  petals  are  very 
large,  very  broad,  moderately  tumid,  well  apart  at  the  ends,  subequal  in  length.  The  poriferous 
zones  are  very  wide,  the  inner  row  of  pores  moderately  elevated  above  the  outer. 

The  interambulacral  areas  are  very  narrow,  especiaUy  at  the  margin,  where  they  are  only 
about  one-third  as  -wide  as  the  ambulacral  areas. 

'  See  Michelin's  Monographie  des  Clyp&stres,  p.  115,  PI.  XVII,  figs.  la-f. 


220  MESOZOIC    AND    CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

The  apical  system  is  central,  coincident  .with  the  apex,  about  on  a  level  with  the  highest 
portions  of  the  ambulacral  petals.  The  specimen  is  too  weathered  to  permit  of  making  out 
the  details. 

The  peristome  is  large,  subpentagonal,  central,  at  the  deepest  point  of  the  concavity  on  the 
under  surface.  The  ambulacral  furrows  are  simple,  straight  shallow  grooves  extending  from 
the  peristome  nearly  to  the  margin. 

The  periproct  is  large,  circular,  inframarginal,  almost  marginal. 

Dimensions. — Length  134  millimeters;  width  116  miOimeters;  height  50  miUimeters. 

Related  jorms. — It  is  unnecessary  to  discuss  here  the  related  recent  forms.  The  nearest 
fossil  form  is  Diflothecanthus  dalJi,  which  is  to  be  distinguished  by  being  relatively  higher,  in 
having  the  apex  slightly  excentric  posteriorly  and  angular,  with  a  straighter  slope  anteriorly 
and  a  steeper  slope  posteriorly,  in  having  the  apical  system  sloping  downward  anteriorly,  and 
in  having  the  interi^oriferous  areas  more  tumid  and  coalescing  around  the  madreporite. 

Locality. — Near  LabeUe  Landing,  Caloosahatchee  River,  Fla. 

Geologic  horizon. — Pliocene  (?). 

Collection. — U.  S.  National  Museum  (16569.3). 

Order  ATELOSTOMATA. 

Suborder  ASTERNATA, 

FamUy  CASSIDULID^. 

Genus  CASSIDTJLTIS  Lamarck. 

Cassidulus  berryi  Twitchell,  n.  sp. 

Plate  CI,  figures  3a-d. 

Determinative  characters. — Test  small,  subcircular  in  marginal  outline;  upper  surface  much 
dej^ressed,  convex;  sides  and  ends  equally  and  gently  dechning;  margin  angular,  posterior  end 
rostrated;  under  surface  concave,  more  so  anteriorly  around  the  peristome.  Apex  central; 
apical  system  excentric  anteriorly.  Ambulacral  areas  rather  broad  in  petaloidal  dorsal  portions, 
very  narrow  above  the  margin.  Peristome  small,  anteriorly  excentric,  pentagonal,  with  a 
floscelle.     Periproct  oval,  supramarginal,  in  a  short,  shallow  sulcus. 

Dimensions. — Length  2S  millimeters;  width  27  millimeters;  height  11  millimeters. 

Description. — The  only  specimen  of  this  species  so  far  reported  was  found  recently  in  North 
Carolina  by  E.  W.  Berry,  of  Johns  Hopkins  University,  in  whose  honor  the  species  is  named. 
Unfortunately,  the  specimen  is  damaged,  so  that  a  number  of  important  details  can  not  be  made 
out;  but  the  characters  which  can  be  made  out  prove  it  to  be  distinct  from  the  other  American 
representatives  of  the  genus.  The  test  is  small,  about  an  inch  in  diameter;  subcircular  in 
marginal  outline,  the  longitudinal  diameter  slightly  exceeding  the  transverse.  The  upper  sur- 
face is  much  depressed,  convex,  sides  and  ends  equally  and  gently  dechning;  margin  rather 
sharply  angular  all  aroimd ;  posterior  end  rostrated  and  faintly  notched  beneath  the  periproct; 
under  surface  concave,  more  so  anteriorly  around  the  peristome  than  elsewhere.  The  apex 
is  central. 

The  ambulacral  areas  are  rather  broad  in  the  petaloid  dorsal  portions,  very  narrow  above 
the  margin  and  actinally;  the. petals  are  rather  broad,  subeUiptical,  subequal  in  length,  nearly 
closing  at  the  ends.     Tlie  details  are  obscure. 

The  apical  system  is  excentric  anteriorly.     Tlie  details  can  not  be  made  out  on  the  specimen. 

The  peristome  is  small,  anteriorly  excentric,  beneath  the  apical  system,  pentagonal,  with  a 
floscelle  having  prominent  bourrelets. 

The  periproct  is  oval,  longitudinally  elongate,  supramarginal,  in  a  short,  rather  wide,  shal- 
low sulcus,  which  extends  to  and  faintly  notches  the  posterior  margin. 


PLIOCENE   ECHINODEBMATA.  221 

Related  forms. — The  nearest  related  American  form  is  Cassidulus  hassleri,  from  which  it  is 
readily  distinguished  by  its  more  depressed  form,  its  angular  margin,  and  the  anteriorly  excentric 
position  of  its  peristome. 

Locality. — Neills  Eddy  Ijanding,  Cape  Fear  River,  N.  C. 

Geologic  liorizon. — Waccamaw  mai-1,  Phocene. 

Collections. — U.  S.  National  Museum;  Johns  Hopkins  University  (T  1). 

Suborder  STERNATA. 
Family  SPATANGID^. 

Genus  SCHIZ ASTER  Agassiz. 

ScHiZASTER  (?)  STALDEEi  Weaver. 

Plate  cm,  figure  2. 

Schizaster  (?)  stalderi  Weaver,  1908,  California  Univ.  Dept.  Geology  Bull.,  vol.  5,  No.  17,  p.  274,  PL  XXI,  fig.  3. 
Schizaster  stalderi  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  705. 

Description. — Weaver  says : 

Test  distinctly  cordate  in  form,  with  all  of  the  petals  deeply  sunken.  The  depression  of  the  anterior  petal  deeply 
notches  the  anterior  margin.  The  petals  of  the  hivium  are  very  short.  The  mouth  opening  is  situated  very  far  for- 
ward. The  anal  opening  is  not  shown.  As  all  of  the  known  specimens  are  casts,  the  nature  of  the  plates  of  the  test  is 
only  imperfectly  shown. 

Dimensions. — Maximum  length  30.5  millimeters;  maximum  widtli  28  millimeters. 
Locality. — Humboldt  County,  Cal. 
Geologic  horizon. — Wildcat  series  of  Ijawson,  Pliocene. 

Collection. — University  of  California.  ' 

39800°— 15 15 


PLEISTOCENE   ECHINODERMATA. 
Class  STELLEROIDEA. 
Subclass  ASTEROIDEA. 
Order  CRYPTOZONIA. 

Family  ASTERIIDiE. 
Genus  ASTEBIAS  Linne. 
ASTERIAS    STELLIONUEA    Poiret. 
Asterias  stellionura  Sears,  1905,  Physical  geography,  etc.,  Essex  County,  Mass.,  pp.  369,  370. 

Description. — Sears  describes  the  discovery  in  1903  in  the  Richard  Graham  clay  pit  at 
Lynn,  Mass.,  of  a  thick  bed  of  fossil  starfish,  material  from  which  was  collected  and  sent  to 
A.  E.Verrill,  of  Yale  University,  for  identification.  Of  the  two  forms  fomid  one  is  miqu&stionably 
referred  to  A.  stellionura.  Verrill  states  that  "the  pedicellariae,  both  major  and  minor,  are 
remarkably  well  preserved  and  very  characteristic,"  and  that  "it  is  a  very  arctic  species,  com- 
mon at  Spitzbergen  and  the  northern  Norwegian  coasts." 

Locality. — Richard  Graham  clay  pit,  Lynn,  Mass. 

Geologic  horizon. — Pleistocene. 

Collection. — Peabody  Museum,  Salem,  Mass. 

Asterias  lincki  Miiller. 

Astemcanthion  lincki  Sears,  190.5,  Physical  geography,  etc.,  Essex  County,  Mass.,  pp.  369,  370,  fig.  202. 
Description. — Verrill  says: 

The  pedicellariae,  both  major  and  minor,  are  remarkably  well  preserved  and  very  characteristic.  On  theAstera- 
canthion  the  latter  form  large  and  dense  clusters  around  all  the  spines.  The  same  appears  in  your  fossils.  The  major 
ones  are  very  large,  ovate,  subacute,  especially  along  the  adambulacral  plates,  but  also  many  of  the  dorsal  surfaces  as 
in  your  examples.  Dorsal  plates  are  very  delicate  and  form  a  slender  network.  Adambulacral  spines  are  small  and 
slender,  tapered,  acute,  and  a  large  tubed  spine  stands  siiigly  back  of  every  fourth  or  fifth  plate  (sometimes  third  or 
fourth)  as  in  yours.     In  all  of  these  characters  and  others  it  differs  from  A.  vulgaris. 

Locality. — Richard  Graham  clay  pit,  Lynn;  Liberty  Street,  Dan  vers,  Mass. 

Geologic  Tiorizon. — Pleistocene. 

Collection. — Peabody  Museum,  Salem,  Mass. 

Class  ECHINOIDEA. 

Subclass  REGULARIA  ECTOBRANCHIATA. 

Order  DIADEM  OIDEA. 

Suborder  ECHINTNA. 

Family  TRIPLECHINID.^. 

Genus  TOXOPNETJSTES  A.  Agassiz. 

ToxoPNEUSTES  VARiEGATUs  (Lamarck). 

Echinus  variegatus  Holmes,  1858,  Post-Pliocene  fossils  South  Carolina,  PI.  II,  fig.  1. 
Anapesus  carolinus  Holmes,  1858,  Post-Pliocene  fossils  South  Carolina,  PI.  II,  fig.  2. 
Toxopneustes  variegatus  A.  Agassiz,  1872,  Revision  of  the  Echini,  p.  168. 

Description. — A.  Agassiz  regards  the  form  referred  by  Holmes  to  Anajyesus  carolinus  as 
T.  variegatus.     No  material  has  been  available  for  study. 

Locality.— Simmons  Bluff,  St.  Paul's,  Wando,  and  Charleston,  S.  C.  (Holmes). 
Geologic  horizon. — Pleistocene. 
Collection. — Unknown. 
222 


PLEISTOCENE   ECHINODEEMATA.  223 

Family  STRONGYLOCENTROTID,*!. 

Genus  STRONG YLOCENTBOTXJS  Brandt. 

Stkongylocentrotus  drobachiensis  Miiller. 

(?)  Echinus  granulahi-s,  Billings,  1856,  Canadian  Naturalist  and  Geologist,  1st  ser.,  vol.  1,  p.  346. 
Slrongylocentrotus  drobachiensis  Verrill,  1875,  Am.  Jour.  Sci.,  3d  ser.,  vol.  10,  p.  375. 
Strongylocentrotus  drobachiensis  Cooper,  1894,  California  Min.  Bur.  Bull.  4,  p.  32. 

Description. — Fragments  of  tests  and  spines  regarded  as  representing  this  species  have  been 
reported  from  Pleistocene  deposits  from  Nantucket  northward  and  also  in  California. 

Localities. — Canada  (Billings);  Sankaty  Head,  Nantucket,  Mass.  (Verrill);  San  Nicolas 
Island,  Cal.  (Burns). 

Geologic  horizon. — Pleistocene. 

Collection. — Unknown. 

Strongylocentrotus  franciscanus  A.  Agassiz. 

Strongylocentrotus franciscanus  Arnold,  1903,  California  Acad.  Sci.  Mem.,  vol.  3,  p.  90. 
Strongylocentrotus  franciscanus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  706. 

Description. — Arnold  in  discussing  the  occurrence  of  this  species  in  the  Pacific  coast  Pleis- 
tocene says: 

This  is  the  large  aea  urchin  of  the  west  coast.  Spines  which  are  probably  of  this  species  have  been  found  in  the 
lower  San  Pedro  series  of  Deadman  Island.  The  spines  of  this  species  are  distinguishable  by  their  large  size  and  longi- 
tudinal striations.     Some  of  the  spines  found  are  20  millimeters  long  and  3  millimeters  in  diameter. 

Locality. — San  Pedro,  Cal. 

Geologic  horizon. — San  Pedro  formation  (lower  part),  Pleistocene. 

Collection. — Leland  Stanford  Junior  University. 

Strongylocentrotus  purpuratus  (Stimpson). 

Strongylocentrotus  purpuratus  Arnold,  1903,  California  Acad.  Sci.  Mem.,  vol.  3,  pp.  90,  91. 
Strongylocentrotus  purpuratus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Description. — Arnold,  who  mentions  the  discovery  of  spines  of  this  species  in  the  Cali- 
fornia Pleistocene,  says: 

Numerous  spines  of  this  small  purple  sea  urchin  have  been  found  in  the  San  Pedro  series.  No  part  of  the  test 
ha.s  ever  been  discovered  in  these  deposits,  to  the  writer's  knowledge,  Several  nearly  perfect  tests  of  this  species  were 
found  in  the  Pleistocene  (lower  San  Pedro  series)  deposits  at  the  bathhouse,  Santa  Barbara.  A  nearly  perfect  test 
was  also  found  in  the  upper  horizon  of  the  San  Diego  formation  (Pleistocene  (?)  )  at  Pacific  Beach,  near  San  Diego. 

Localities. — San  Pedro,  Santa  Barbara,  and  San  Diego,  Cal. 

Geologic  horizon.— San  Diego  formation  (upper  part),  PHocene;  San  Pedro  formation 
(lower  part),  Pleistocene. 

Collection. — Leland  Stanford  Junior  University. 

Subclass  IRREGULARIA. 

Order  GNATHOSTOMATA. 

Suborder  CLYPEASTRINA. 

Family  SCUTELLID.*;. 

Dendraster  excentricus  (Eschscholtz) . 

Plate  CIV,  figures  la-d;  Plate  CV,  figures  la-d. 

Scutella  striatula  De  Serres,  1829,  G6ognosie  terr.  tert.  du  midi  de  France,  p.  156. 

Scutella  excentrica  Eschscholtz,  1831,  Zool.  atlas,  p.  19, PI.  XX,  figs.  2,  2a,  2b. 

Echinarachnius  excentricus  Valenciennes,  1846,  Voyage  Venus,  Zooph.,  PI.  X. 

Dendraster  excentricus  L.  Agassiz,  1847,  Cat.  raisonne  des  ^chiuodermes,  Soc.  Nat.  Ann.,  vol.  7,  p.  135. 

Dendraster  excentricus  Gray,  1855,  Cat.  Recent  echinoderms,  p.  16. 

Dendraster  excentricus  Stimpson,  1857,  Boston  Soc.  Nat.  Hi.st.  Jour.,  vol.  6,  pp.  520-527. 


224  MESOZOIC   AND   CENOZOIC    ECHINODEEMATA    OF    THE    UNITED    STATES. 

Scutella  striatula  Conrad,  1857,  U.  S.  Pacific  R.  R.  Expl.  32d  Par.  and  California,  vol.  7,  pi.  IX,  figs,  la,  lb;  non 

Dendraster  excentricus  Dujardin  and  Hupe,  1862,  Hist.  nat.  zoophytes  ^chinodermes,  p.  564. 

Scutella  striatula  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 

Scutella  striatula  Gabb,  1869,  California  Geol.  Survey.  Paleontology,  vol.  2,  p.  110. 

Scutella  (Echirmrachnius)  excentricus  A.  Agassiz,  1S72,   Revision  of  the  echini,  Mus.  Comp.  Zoology  Illus.  Cat.  No.  7, 

pp.  107,  524-526.     PI.  Xllla,  figs.  1  to  4. 
Echinarachnius  excentricus  Cooper,  1888,  Cat.  California  fo.ssils:  State  Mineralogist  Seventh  Rept.,  p.  271. 
Echinarachnius  excentricus  Gregory,  1891,  Geol.  Soc.  America  Bull.,  vol.  3,  p.  107. 
Echinarachnius  excentricus  Memam,  1899,  California  Acad.  Sci.  Proc,  3d  ser..  Geology,  vol.  1,  No.  5,  p.  170,  PL  XXiI, 

fig.  8. 
Scutella  {Echinarachnius)  excentricus  Arnold,  1903,  California  Acad.  Sci.  Mem.,  vol.  3,  p.  91. 
(?)  Echinarachnius  excentricus   Eschscholtz  var.  Arnold,  1907,  U.  S.  Geol.  Survey  Bull.  322,  PI.  XXIV,  fig.  8.     [This 

is  probably  a  vai'iant  form  of  Dendraster  gibbsii.) 
Scutella  striatula  Schuchert,  1908,  U.  S.  Nat.  Mus.  Bull.  53,  pt.  1,  p.  594. 

Echinarachnius  excentricus  Pack,  1909,  California  Univ.  Dept.  Geology  Bull.,  vol.  5,  No.  18,  pp.  2?1-2S2. 
Dendraster  excentricus  Stefanini,  1911,  Soc.  geol.  italiana  Boll.,  vol.  30,  p.  707. 

Determinative  characters. — Test  medium  to  large;  subcircular  to  broadly  subovate  in  margi- 
nal outline,  broader  posteriorly  than  anteriorly;  upper  surface  gi-eatly  depressed  around  the 
margin,  more  or  less  tumid  centrally;  margin  thin;  under  surface  flat.  Apex  central  or  sub- 
central.  Apical  system  excentric  posteriorly;  from  one-fourth  to  one-third  the  radius  from 
the  center.  Ambulacral  petals  large;  posterior  pair  shorter  than  the  others,  less  divergent, 
equally  divergent,  or  slightly  more  divergent  than  the  anterior  pair.  Peristome  small,  circular, 
central  or  subcentral;  ambulacral  furrows  fork  near  the  peristome,  the  branches  at  first  diverg- 
ing then  converging  shghtly,  each  giving  off  one  important  and  many  small  branches  on  the  way 
to  the  margin.  The  stronger  branches  continue  abactinally,  but  they  are  rarely  discernible 
on  fossil  specimens.     Periproct  very  small,  circular  or  subeUiptical,  inframarginal. 

Dimensions. — Specimen  A:  Length  83  millimeters;  width  S.3  millimeters;  height  12  milli- 
meters.    Specimen  B:  Length  97  millimeters;  width  105  millimeters;  height  19  millimeters. 

Description. — This  well-knowm  Recent  form,  abundant  on  the  Pacific  coast,  is  so  fully 
described  in  other  works,  that  it  is  necessary  to  give  here  onty  the  special  points  of  interest  in 
regard  to  the  fossil  specimens.  Most  of  these  have  already  been  given  in  the  determinative 
characters,  but  a  few  additional  details  will  be  presented.  The  size  varies  from  less  than  2  to 
more  than  4  inches  in  diameter  and  less  than  one-fourth  to  about  1  inch  in  height.  In  marginal 
outline  the  smaller  forms  are  usually  subcircular  while  the  large  ones  are  usually  broadly  subovate 
and  broader  than  loiag.  The  apex  is  usually  between  the  center  and  the  apical  system,  but  is 
sometimes  central  or  shghtly  excentric  anteriorly.  The  area  between  the  ends  of  the  petals 
and  the  margin  is  wider  than  in  forms  which  resemble  this.  The  under  surface  is  flat  or  shghtly 
concave. 

The  ambulacral  areas  are  wide,  widest  at  the  margin,  where  they  are  wider  than  the  inter- 
ambulacral  areas;  dorsal  portions  petaloid,  the  petals  somewhat  variable  in  details.  The  petals 
are  large,  the  anterior  three  longer  than  the  posterior  pair,  the  odd  petal  longer  than  the  anterior 
paired  petals,  though  sometimes  appearing  of  equal  length  or  shorter  by  reason  of  the  shortening 
of  the  distance  between  the  pairs  of  pores  of  the  poriferous  zones  for  a  greater  or  less  distance 
from  the  end  of  the  petal.  The  anterior  paired  petals  are  straight  or  nearly  so  and  more  widely 
divergent  or  equally  divergent  or  shghtly  less  divergent  than  the  posterior  pair.  The  posterior 
pair  is  usually  less  widely  divergent  and  the  ]5oriferous  zones  of  each  petal  are  less  widely  diver- 
gent than  in  similar  forms.  The  interporiferous  areas  of  all  the  petals  are  rather  wide  and  some- 
what tumid. 

The  apical  system  is  excentric  posteriorly,  being  situated  from  one-fourth  to  one-third  the 
distance  from  the  center  to  the  posterior  margin ;  the  madreporite  is  large  and  substellate  with 
four  genital  pores  at  the  anterior  points  of  the  star,  the  two  anterior  nearer  together  than  the 
two  posterior.     There  are  also  five  small  radial  plates  each  perforated  by  a  minute  pore. 

The  peristome  is  central  or  slightly  excentric  posteriorly.  The  ambulacral  furrows  are  simple 
and  straight  for  a  very  short  distance  from  the  peristome,  then  fork  nearly  symmetrically  into 


PLEISTOCENE   ECHINODEEMATA.  225 

two  strong  furrows  which  diverge  for  a  short  distance  then  converge  slightly  and  continue 
nearly  to  the  margin,  giving  off  one  large  and  many  small  branches  on  the  way.  Near  the 
margin  the  large  furrows  sjjlit  up  into  many  small  ones  which  on  weU-preserved  fossil  specimens 
and  in  recent  specimens  can  be  seen  to  continue  over  the  margin  and  on  the  upper  surface  for  a 
considerable  distance. 

The  periproct  is  very  small,  usually  circular,  but  sometimes  subelliptical  by  longitudinal 
elongation;  situated  from  1  to  10  millimeters  from  the  posterior  border,  being  more  distant  in 
the  large  specimens. 

Related  forms. — D.  excentricus  is  closely  related  to  both  D.  coalingaenms  and  D.  gibhsii. 

D.  coalingaensis  differs  in  behig  smaller,  more  uniformly  depressed  and  therefore  less  tumid 
centrally,  in  having  its  apex  more  excentric  posteriorly  and  more  nearly  coincident  with  the  apical 
system  and  its  pei-iproct  usually  nearer  the  margin.  The  features  in  which  D.  coalingaensis 
resembles  D.  excentricus  are  so  fundamental  as  to  suggest  that  it  is  probably  an  ancestral  form. 
D.  gihhsii  differs  from  D.  excentricus  in  having  its  apex  and  apical  sj'stem  much  more  excentric 
posteriorly,  its  posterior  ambulacral  petals  more  widely  divergent  and  with  poriferous  zones 
also  diverging  more  widely  from  each  other  as  well  as  differing  more  in  length  and  its  peri])roct 
usually  nearer  the  posterior  border.  There  do  not  appear  to  be  any  foreign  forms  closely  related 
to  the  present  species. 

Localities. — San  Diego  (figured  specimen  A) ;  Ventura  County  (figured  specimen  B) ;  San 
Luis  Obispo  (Conrad's  type);  Riverside  County;  San  Pedro  (Cooper,  Arnold),  Santa  Barbara 
(Gabb,  Arnold);  Seven  Mile  Beach,  San  Mateo  County  (Cooper);  San  Fernando,  Los  Angeles 
Cormty  (Cooper);  all  in  California. 

Geologic  horizon. — San  Pedro  formation,  Pleistocene. 

Collections. — Wagner  Free  Listitute  of  Science  (2473,  A);  U.  S.  National  Museum;  Yale 
University;  California  Academy  of  Natural  Sciences;  Johns  Hopkins  University  (T  2,  B). 

Genus  MELLITA  Agassiz. 

Mellita  pentapora  (Gmehn). 

Plate  CVI,  figure  1;  Plate  CVII,  figures  la-c. 

Echinus  pentaporus  Gmelin,  1788,  Linne,  Systema  naturae,  vol.  1,  pt.  6,  p.  3189. 

Mellita  testudinata  Klein,  1734,  Nat.  disp.  Echinodermata,  p.  25,  PI.  XXI,  fig.  C,  D.    (Copied  in  Enc.  M.,  PI.  CXLIX, 

figs.  3,  4.) 
Scutella  quinquefora  Lamarck,  1816,  Animaux  sans  vertebres,  p.  9. 
Scutella  quinquefora  Lamarck,  1840,  Animaux  sans  vertlbres,  2d  ed.,  p.  280. 

Mellita  testudinata  Agassiz,  1841,  Mon.  echinodermes  vivans  et  fossiles,  Des  scutelles,  p.  40,  PI.  IV,  figs.  7-9. 
Mellita  quinquefora  Agassiz,  1841,  Mon.  echinodermes  vivans  et  fossiles,  Des  scutelles,  p.  36,  PI.  III. 
Mellita  ampla  Holmes,  1847?     MS. 

Mellita  ampla  Raveuel,  1848,  Echinidae,  recent  and  fossil.  South  Carolina,  p.  2. 
Mellita  ampla  Tuomey,  1848,  Rept.  Geology  South  Carolina,  p.  205. 
Mellita  ampla  Ravenel,  1850,  Am.  Assoc.  Adv.  Sci.  Proc,  vol.  3,  jj.  160. 
Mellita  ampla  Michelin,  1855,  Soc.  geol.  France  Bull.,  2d  ser.,  vol.  12,  p.  759. 
Mellita  texana  Conrad,  1856,  Acad.  Nat.  Sci.  Philadelphia  Proc,  vol.  8,  p.  316. 
Mellita  testudinata  Desor,  1858,  Synopsis  des  echinodermes  fossiles,  p.  237. 
Mellita  ampla  Michelin,  1858,  Rev.  et  mag.  zool.,  2d  ser.,  vol.  10,  pp.  362,  363,  PL  IX,  fig.  1. 
Mellita  quinquefora  var.  ampla  Holmes,  1860,  Post-Pliocene  fossils  South  Carolina,  pp.  3,  4,  PL  I,  fig.  6. 
Mellita  ampla,  Dujardin  and  Hupe,  1862,  Hist.  nat.  zoophj-tes  echinodermes,  p.  567. 
Mellita  pentapora  Liltken,  1864,  Bid.  til  Kunds.  om  Echinodermes,  Vidensk.  Medd.  Kj0benhavn. 
Mellita  texana  Meek,  1864,  Smithsonian  Misc.  Coll.,  vol.  7  (183),  p.  2. 
Mellita  testudinata  Agassiz,  1872,  Re-\-ision  of  the  Echini,  pp.  141,  142. 

Mellita  testudinata  Hilgard  and  Hopkins,  1878,  Rept.  Com.  Engineers  of  Jan.  1875;  suppL,  pp.  23-33,  49,  PL  III,  fig.  12. 
Mellita  pentapora  Clark,  1902,  U.  S.  Fish  Com.  Bull.,  p.  565,  PL  X. 
Mellita  ampla  Stefanini,  1911,  Soc.  geol.  itaUana  Boll.,  vol.  30,  p.  708. 

Determinative  cliaracters.— Test  medium  to  very  large;  subpeutagonal  in  marginal  outhne, 
broadest  opposite  anterior  paired  petals;  five  long  narrow  lunules  equal  or  subequal  in  length; 
margin  thin,  with  a  shallow  notch  at  the  anterior  end ;  the  whole  form  much  depressed,  the  upper 


226  MESOZOIC   AND   CENOZOIC   ECHINODEKMATA    OF    THE    UNITED    STATES. 

surface  rising  gradually  from  the  margin  to  the  moderately  elevated,  anteriorly  cxcentric  apex; 
under  surface  flat.  Ambulacral  petals  large,  the  posterior  pair  longer  than  the  others.  Apical 
system  excentric  anteriorly.  Peristome  small,  subcircular,  excentric  anteriorly;  ambulacral 
furrows  simple  and  straight  near  the  peristome,  then  forking,  each  pair  of  branches  diverging 
and  again  converging  near  the  margin.  Periproct  very  small,  elliptical,  between  the  inner  end 
of  the  odd  lunule  and  the  peristome. 

Dimensions. — Figured  specimen,  one  of  the  largest  found:  Length  152  millimeters;  width 
159  millimeters;  height  19  millimeters.  Smaller  specimen;  Length  106  millimeters;  width  111 
millimeters;  height  12  milUmeters. 

Description. — The  specimens  herein  described  are  believed  to  be  representatives  of  the 
recent  species  Mellita  penta/pora  (Gmelin)  which  has  been  known  under  the  names  of  M.  testu- 
dinata  Klein  and  M.  quinquefora  Lamarck.  Evidently,  as  Holmes  recognized,  the  conditions 
were  especially  favorable  to  development  along  the  South  Carolina  coast  during  Pleistocene 
time,  a  fact  which  is  shown  by  the  large  size  of  the  molluscan  forms  as  well  as  by  the  Echinidse. 

As  this  well-known  recent  species  is  fully  described  in  other  works,  it  is  necessary  to  give 
here  only  the  special  points  of  interest  in  regard  to  the  specimens  occurring  as  fossils.  Conrad's 
species  Mellita  texana,  of  which  what  is  probably  the  type  is  in  the  collection  of  the  Academy 
of  Natural  Sciences  of  Philadelphia,  presents  no  marked  and  constant  points  of  difference 
from  the  recent  species  and  therefore  can  not  be  recognized.  Holmes's  variety  ampla  is  not 
entitled  to  separate  recognition  and  description,  as,  aside  from  the  unusual  size  of  the  South 
Carolina  specimens,  there  are  no  decided  and  constant  differences.  Some  specimens  of  the 
so-called  variety  ampla  present  differences  in  regard  to  the  lunules  which  make  them  appear 
varietal  in  value,  but  a  careful  study  of  the  large  number  of  specimens  in  the  collections  of  the 
United  States  National  Museum  and  the  Johns  Hopkins  University  has  demonstrated  that 
the  form  of  the  lunules  is  so  variable  as  to  be  unsafe  as  a  feature  for  separation.  This 
species  is  very  abundant  and  occurs  in  a  beautiful  state  of  preservation  at  a  few  localities  in. 
South  Carolina,  but  is  rare  elsewhere.  Most  of  the  important  features  of  the  test  have  been 
set  forth  in  the  determinative  characters,  but  a  few  additional  details  will  be  given  here.  The 
size  of  the  fossil  forms  from  South  Carolina  is  very  great,  ranging  from  4  to  7  inches  in  diame- 
ter and  from  i  to  |  inch  in  height,  while  those  from  Texas  are  rather  small,  being  between  2  and 
3  inches  in  diameter,  which  is  about  the  same  as  that  of  the  average  recent  forms.  The  test  is 
usually  sUghtly  broader  than  long.  The  margin  is  truncated  and  especially  thin  posteriorly. 
The  lunules  are  long  narrow  slits  of  about  the  same  width  from  end  to  end,  bluntly  rounded 
at  the  ends,  the  length  and  width  quite  variable  even  on  the  same  specimen,  the  odd  posterior 
lunule  usually  wider  .and  of  equal  length  or  slightly  longer  or  shorter  than  the  rest;  the  average 
length  in  the  South  Carohna  forms  is  about  1  inch  and  the  width  one-eighth  of  an  inch.  The 
petaloid  region  is  large;  the  petals  are  long  and  wide,  subelliptical  to  subspatulate  in  form, 
extending  about  halfway  to  the  margin,  well  open  at  then'  ends,  vnth  very  broad  poriferous 
zones  which  about  equal  in  ^vidth  the  interijoriferous  areas.  The  apical  system  is  large;  madre- 
porite  large  and  stellate;  four  genital  pores  at  the  tips  of  the  points  of  the  star,  the  two  pos- 
terior farthest  apart;  five  small  pores  at  inner  ends  of  reentrant  angles  of  the  star.  The  main 
branches  of  the  ambulacral  furrows  ai'e  more  or  less  flexuous  and  each  branch  gives  off  one 
important  lateral  branch  as  it  bends  to  approach  the  margin.  The  undersurface,  though  flat 
in  general,  has  shallow  grooves  along  the  middle  of  each  ambulacrum. 

Related  forms. — The  only  American  fossil  form  which  is  closely  related  to  the  present 
species  is  Mellita  caroliniana  which,  however,  is  readily  distinguished  by  its  having  a  sixth 
lunule  in  the  middle  of  the  anterior  ambulacrum,  by  having  its  ambulacral  lunules  nearer  the 
margm  and  its  posterior  paired  lunules  longer  than  the  anterior  pair;  and  having  the  relative 
height  of  its  test  less  than  in  M.  pentapora. 

Localities. — Simmons  Bluff,  Youngs  Island,  Wadmalaw  Sound,  S.  C;  Brunswick  Canal, 
Glynn  County,  Ga. ;  Texas  (  ?). 

Geologic  horizon. — Pleistocene. 


PLEISTOCENE    ECHINODEKMATA.  227 

Collections. — Johns  Hopkins  University  (T  2,  T  4);  American  Museum  of  Natural  History; 
U.  S.  National  Museum;  Wagner  Free  Institute  of  Science;  Academy  of  Natural  Sciences  of 
Philadelphia. 

Order  ATELOSTOMATA. 

Suborder  STERNATA. 

Family  SPATANGID^. 

Genus  SCHIZASTER  Agassiz. 

ScHizASTER  ATROPOS  (Lamarck). 

Schizaster  atropos  Ravenel,  1848,  Echinidse,  recent  and  fossil,  South  Carolina,  p.  4. 
Schizas'er  atropos  Holmes,  1858,  Post-Pliocene  fossils  South  Carolina,  pp.  5,  6,  PL  II,  fig.  3. 
M(em  lachesis  Desor,  1858,  Synopsis  echinides  fossOes,  p.  394. 
Schizaster  atropos  A.  Agassiz,  1874,  Revision  of  the  Echini,  p.  751. 

Description. — No  material  has  been  found  that  can  be  referred  to  this  species. 
Locality. — Abbapoola  Creek,  Johns  Island,  S.  C.  (Holmes). 
Geologic  Jiorizon. — Pleistocene. 
Collection. — Unknown. 


PLATES. 


39800°— 15 16  220 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  I 


la 


lb 


2a 


2c 


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TRIASSIC    CRINOIDEA    AND    ECHINOIDEA. 


PLATE   I. 

IsocRiNUS  sMiTHi  Claik,  n.  sp.  (p.  21). 

U.  S.  Nat.  Mus.  31184,  type. 

Figure  la.  Articular  surface  of  a  detached  joint  of  the  column,  X  4. 
lb.  Lateral  view  of  a  detached  joint  of  the  column,  X  4. 

ISOCRINUS   CAUFORNICUS   Claik,  11.  sp.   (p.  21). 

U.  S.  Nat.  Mus.  31185,  type. 

Figure  2a.  Articular  surface  of  a  detached  joint  of  the  column,  X  6. 
2b.  Lateral  view  of  a  portion  of  the  column,  X  6. 
2c.  Several  specimens  of  column  joints. 

Encrinus  hyatti  Clark,  n.  sp.  (p.  22). 

U.  S.  Nat.  Mus.  31186,  type. 

Figure  3a.  Articular  surface  of  a  detached  joint  of  the  column,  X  If. 
3b.  Lateral  view  of  a  portion  of  the  column,  X  If. 

AsPiDURA  (?)  iDAHOENSis  Clark,  11.  sp.  (p.  23). 

U.  S.  Nat.  Mus.  31187,  type. 
Figure    4.  Cast  of  two  specimens. 

CiBARis  SHASTENsrs  Clark,  n.  sp.  (p.  2.3). 

U.  S.  Nat.  Mus.  31188,  type. 

Figure    5.  Fragment  of  interambulacral  plate,  X  3. 

CiDARis  DiLLERi  Clark,  n.  sp.  (p.  23). 

U.  S.  Nat.  Mus.  31189,  type. 
Figure    6.  Portion  of  test. 
230 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  I 


JURASSIC    CRINOIDEA. 


PLATE   II. 

IsoCRiNUS  KNiGHTi  Springer  (p.  25). 

U.  S.  Nat.  Mus.  Springer  A-H,  type.     (After  Springer.) 

Figure    1.  Large  specimen  A;  with  bifurcating  arms  complete  and  i>art  of  stem;  cirri  mostly  lost, 
la.  Syzygy  at  IIIBr  79+80  of  same  specimen. 

2.  Large  specimen,  B,  with  stem  140  millimeters,  and   part  of  arms.     Some  arms  of    another   individual 

attached. 
2a.  Detail  of  stem  at  "a"  of  same  specimen,  showing  interarticular  pores,  X  2. 
2b.  Detail  of  same  at  "b",  showing  cirrus  sockets,  X  2. 

3.  Small  specimen,  C,  with  part  of  arms,  some  not  bifurcating. 

3a.  Calyx  and  lower  IIIBr  of  same  specimen,  showing  form  and  proportions  of  basal  and  radial  plates,  X  2. 

4.  Small  specimen,  D,  with  part  of  arms,  one  with  an  axillary,  and  some  apparently  simple. 

5.  Small  specimen,  E,  with  two  arms  simple  and  one  bifurcating  at  23d  IIIBr,  stem  detached,  exposing 

infrabasals. 
5a.  Basal  view  of  same  specimen,  showing  infrabasals,  X  4. 
6-8.  Portions  of  different  stems,  F,  G,  H,  showing  cirri. 

7a.  The  longest  cirrus  on  specimen  G,  X  2. 
9-13.  Weathered  stem  joints  associated  with  the  other  specimens:  9,  10,  11  are  mature  inlernodals:  12  is  the 
proximal  face  of  a  nodal  incised  by  the  cirrus  sockets;  13  is  a  deeply  stellate  joint  from  the  youngest  part 
of  the  stem;  all  X  2. 

231 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  III 


^^ 

;^af 

-JS 

£^ 

£^^1^ 

s 

3c 


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.,^r. 


JURASSIC    CRINOIDEA    AND    STELLEROIDEA. 


PLATE   III. 

IsocRiNUS  KNiGHTi  Springer  (p.  25). 
U.  S.  Nat.  Mus.  682. 

Figure  la.  Column  with  attached  piiinule.s. 

lb.  Articular  .surface  of  a  detached  joint  of  the  column,  X  4. 

Ic.  Lateral  view  of  a  portion  of  the  column,  X  4. 

Id.  Enlarged  pinnule,  X  2. 

Pentaceinus  asteriscus  Meek  and  Hayden  (p.  26). 
II.  S.  Nat.  Mus.  220,  type.     (After  Meek  and  Hayden.) 
Figure    2.  Upper  surface  of  a  detached  joint,  X  5. 

Pentacrinus  whitei  Clark  (p.  27). 

U.  S.  Nat.  Mus.  8588,  type. 

Figure  3a.  Articular  surface  of  a  detached  joint  of  the  column,  X  2. 
3b.  Same,  X  2. 
3c.  Lateral  view  of  a  portion  of  the  column. 

Pentaceinus  shastensis  Clark,  n.  sp.  (p.  2S). 

U.  S.  Nat.  Mus.  31180,  type. 

Figure    -1.  Articular  .surface  of  a  detached  joint  of  the  column,  X  3. 

Ophioglypha  utahexsis  Clark,  n.  sj).  (p.  29). 

U.  S.  Nat.  Mus.  22839,  tyi^e. 

Figure    5.  Upper  surface  of  specimen,  X  3. 

Asterias  (?)  DUBiuM  Whitfield  (p.  28). 

U.  S.  Nat.  Mus.  12325,  type. 

Figure    6.  Gutta-percha  cast  of  three  individuals. 
232 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV     PLATE  IV 


Ic 


4b 


1 1 


4d 


JURASSIC     ECHINOIDEA. 


PLATE    IV. 

CiDAKis  cALiFORNicus  Clark  (p.  30). 

II.  S.  Nat.  Mus.  30184,  tyi>e. 
Figure  la.  Spine, 
lb.  Same. 
Ic.  Articular  surface  of  lb,  X  2. 

CiDARIS  TAIXOKENSIS  Clark    (j).   30). 

U.  S.  Nat.  Mus.  30183,  tyjje. 

Figure  2a.   Fragment  containing  two  contiguous  interambulacral  plates  of  tlie  same  series. 
2b.  Spine. 

CiDARIS  PLUMASENSIS  Clark,  11.  sp.  (p.  31). 

U.  S.  Nat.  Mus.  31191,  type. 
Figure  3.  Portion  of  interambulacral  area. 


Hemicidaris  intumescens  Clark  (j).  31). 
U.  S.  Nat.  Mus.  30187  and  30188,  types. 


Figure  4a.   Upper  surface  of  the  test.     Partly  restored. 
4b.  Lower  surface  of  the  test.     Partly  restored. 
4c.   Lateral  view  of  the  same.     Partly  restored. 
4d.  Two  interambulacral  plates,  X  5. 
4e.   Lower  portion  of  interambulacrum,  X  5. 
4f.    Upper  portion  of  the  same,  X  5. 
4g.   Portion  of  ambulacrum,  X  4. 
4h.  Tubercle  from  above,  X  8. 
4i.    Lateral  view  of  the  same,  X  8. 


233 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  V 


Id 


2e 


2d 


le 


^«^^£^. 


JURASSIC    ECHINOIDEA. 


PLATE  V. 

PsExnJODiADEMA  EMERSONi  Clark  (p.  32). 

U.  S.  Nat.  Mus.  30186,  type. 


Figure  la.   Lateral  surface  of  the  test. 

lb.  Portion  of  interambulacrum,  X  3. 
Ic.    Portion  of  ambulacrum,  X  3. 
Id.  Tubercle  from  the  side,  X  5. 
le.   The  same  from  above,  X  5. 


Stomechinus  hyatti  Clark  (p.  33). 

U.  S.  Nat.  Mus.  30185,  tyije. 


FiGURK  2a.   Lateral  surface  of  the  test,  slightly  distorted. 
2b.  Portion  of  ambulacrum,  X  •!. 
2c.   Portion  of  interambulacrum,  X  -1. 
2d.  Tubercle  from  above,  X  8. 
2e.  The  same  from  the  side,  X  8. 


HoLECTYPUs  PEALEi  Clark,  n.  sp.  (p.  33). 

U.  S.  Nat.  Mus.  31192,  type. 


Figure  3a.   Lateral  surface  of  the  test. 
3b.  Upper  surface  of  the  test. 


HoLECTYPUS  CRAGiNi  Clark,  11.  sp.  (p.  34). 
U.  S.  Nat.  Mus.  31193,  type. 


Figure  4.  Upper  surface  of  the  test. 
234 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV     PLATE  VI 


CRETACEOUS    CRINOIDEA. 


PLATE  VI. 

Pentacrinus  tehamaensis  Clark,  n.  sj).  (p.  35). 

U.  S.  Nat.  Mus.  31194,  type. 

Figure  1.  Articular  surface  of  a  detached  joint  of  the  column,  X  2. 

Pentacrixus  bryani  Gabb  (p.  35). 

Acad.  Nat.  Sci.  Phila.ldphia  145S,  type. 

Figure  2a.   Lateral  view  of  a  portion  of  a  joint  colnmn. 
2b.  Articular  surface  of  the  column. 

Uintacrinus  socialis  GiimioU  (j).  36). 

Mils.  Comp.  Zoolojiy,  ('ambri<lge.     (Figures  after  Springer.) 

Figure  3a.  Monocyclic;  regular;  centrale  of  maximum  size. 
3b.  Monocyclic;  irregular;  double  centrale. 
3c.  Dicyclic;  irregular;  double  centrale  and  1  IB. 
3d.  Dicyclic;  regular;  IBB  fully  developed. 
3e.  Specimen,  with  three  individuals,  showing  dicyclic  and  monocyclic  forms  of   base,  and  maximum  and 

small  size,  lying  together  in  close  contact  on  the  slab;  the  black  membrane  lining  the  calyx  is  also  shown 

at  the  edge  of  the  broken  plates. 
3f.    Uintacrinus  west/aliens  Schlueter.     Figure  of  the  type  specimen  for  comparison  (after  Schlueter). 
3g.   Specimen  laterally  compressed ;  showing  the  fixed  and  proximal  free  pinnules,  and  the  anal  tube  in  natural 

position. 
3h.  Articulating  surfaces  of  brachials,  enlarged  X  2.2;  to  show  the  diagonal  direction  of  the  fulcral  ridges. 

235 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   VII 


CRETACEOUS    CRINOIDEA    AND    STELLEROIDEA. 


PLATE   VII. 
UiNTACRiNUS  sociALis  Grinnell  (p.  36). 

U.  S.  Nat.  Mils.  8044. 
Figure  la.  Lateral  view  of  the  test, 
lb.  Test  showing  pinules. 
Ic.  Part  of  test,  X  2. 

Marsupites  americanus  Springer  (p.  .39). 

Figure  2a.  Side  of  calyx,  with  bases  of  arms,  and  a  strong  interbraehial  passing  in  between  them. 
2b.  Base  of  the  same. 

Collection  of  Frederick  Brawn. 
3.  Infrabasal  plate  of  much  larger  specimen. 
Collection  of  Frank  Springer. 

Rhizocrinus  alabamestsis  (Do  Lnriol)  (p.  39). 

Cincinnati  Soc.  Nat.  Hist.,  type. 
Figure  4a.  Side  of  the  basal  cone. 

4b.  Upper  surface  of  the  same. 
4c.  Lower  surface  of  the  same. 

Rhizocrinus  cylindricus  Weller  (p.  40). 
New  Jersey  Geol.  Survey,  type. 

Figure  5a.  Lateral  view  of  a  complete  body,  X  2. 

5b-g.  Various  sides  of  several  column  j(jiuts,  probably  belonging  to  this  species  (enlarged).     Johns  Hopkins 
Univ. 

Astropecten  (?)  MONTANUS  Douglas  (p.  41). 

Carnegie  Mus.  601,  type. 
Figure  6.  Impression  of  skeleton. 

Pentagonaster  browni  Weller  (p.  41). 

Walker  Mus.,  Chicago,  type. 
Figure  7.  Dorsal  surface  (?). 
236 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  VIII 


CRETACEOUS    STELLEROIDEA. 


PLATE   VIII. 

GONIASTER   MAMMn.LATA   Gabb  (j).  42). 
Acad.  Nat.  Sci.  Philadelphia  1457,  type. 


Figure  la-g.  Various  sides  of  four  different  plates,  X  2. 
Ih.  Surface  of  plate,  X  20. 


Figure  2a.  Tup  of  plate. 
2b.  Side  of  plate. 


Pentaceros  asperulus  Clark  (p.  42). 
Johns  Hopkins  Univ.  T  3014,  type. 

Ophioglyph.4  texana  Clark  (p.  43). 

U.    S.  Nat.  Mus.  21884,  type. 


Figure  3a.  Oral  surface. 

3b.  Portion  of  aboral  surface,  X  5. 
3c.  Portion nf  oral  surface,  X  5. 


Ophioglypha  bridgerensis  (Meek)  (p.  4.3). 
U.  S.  Nat.  Mus.  7820,  type. 


Figure  4a.  Skeleton,  natural  size. 

4b.  Portion  of  the  upper  surface. 

39800^—15 17 


237 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  IX 


CRETACEOUS    ECHINOIDEA. 


PLATE   IX. 

CiDARis  TEHAMAENsis  Clark,  n.  SJJ.  (p.  44). 

U.  S.  Nat.  Mus.  31195,  type. 
Figure  1.  Lateral  view  of  spine. 

CiDARis  TEXANUs  Clark  (p.  45). 

U.  S.  Nat.  Mus.  8381,  type. 
Figure  2a.  Test,  natural  size. 

2b.  Test,  restored,  slightly  enlarged. 

2c.  Arrangement  of  the  interambulacral  plates  in  the  vicinity  of  the  apical  disk,  with  adjacent  ambulacral 

plates.     SUghtly  enlarged. 
2d.  Portion  of  ambulacrum,  X  6. 
2e.  Interambulacral  plate,  sUghtly  enlarged. 
2f.  Tubercle,  X  3. 

CiDARis  WALCOTTi  Clark  (p.  45). 

Acad.  Nat.  Sci.  Philadelphia  1451,  type. 

Figure  3a.  Portion  of  the  test. 

3b.  Interambulacral  plates,  X  2. 
3c.  Portion  of  ambulacrum,  X  8. 
3d.  Tubercle,  X  4. 


CiDARIS    SPLENDENS   Mopton   (p.  46). 
Johns  Hopkins  Univ.  T  3001. 


Figure  4a.  Upper  surface  of  the  test. 
4b.  Lateral  surface  of  the  test. 


CiDARIS    SPLENDENS   Mortoil   (p.  46). 

Acad.  Nat.  Sci.  Philadelphia,  type. 
Figure  5a.  Portion  of  test. 

5b.  Interambulacral  plate,  X  2. 
5c.  Portion  of  ambulacral  area,  X  5. 
5d.  Tubercle,  lateral  view,  X  2. 
5e.  Spine,  X  2. 
5f.  Base  of  same,  X  6. 

CiDARIS    SPLENDENS   Mortoil   (p.  46). 

Johns  Hopkins  Univ.  T  3002. 
Figure  6.  Genital  plate. 

CiDARIS  DixiENSis  Clark,  n.  sp.  (p.  47). 

Geol.  Survey  Texas,  type. 
Figure  7a.  Interambulacral  ])late. 
7b.  Same. 
238 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV     PLATE   X 


le 


If 


y^M 


Ic 


la 


lb 


CRETACEOUS    ECHINOIDEA. 


PLATE  X. 

Leiooidaris  hemigranosus  (Shuniard)   (p.  48). 


Figure  la.  Upper  surface  of  the  test,  X  J. 
lb.  Lower  surface  of  the  test,  X  f. 
Ic.  Lateral  surface  of  the  test,  X  i- 
Id.  Interambulacral  plate, 
le.  Portion  of  ambulacrum,  X  5. 
If.   Tubercles,  X  2. 
Ig.  Apical  system. 


U.  S.  Nat.  Mus.  21768. 


239 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XI 


CRETACEOUS    ECHINOIDEA. 


PLATE   XI. 

Leiocidarls  hemigranosus  (Shumaid)   (p.  48). 
U.  S.  Nat.  Mus.  21768. 


Figure  la.  Upper  surface  of  the  test  restored,  natural  size, 
lb.  Lateral  view  of  the  same. 
240 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV     PLATE  XII 


Id 


li 


t-.-^rff. 


If 


Ih 


le 


Ic 


CRETACEOUS    ECHINOIDEA. 


PLATE  XII. 

Salenia  texana  Crednor  (p.  49). 

U.  S.  Nat.  Mua.  8329,  specimen  A. 

Figure  la.  Lateral  view  of  tlie  test  slightly  enlarged. 

lb.  Upper  surface  of  the  test  restored,  slightly  enlarged. 

Ic.  Lower  surface  of  the  same. 

Id.  Lateral  surface  of  the  same. 

le.  Interambulacrum,  X  3. 

If.    Ambulacrum,  X  4. 

Ig.  Portion  of  the  same,  X  10. 

111.   Tubercle. 

li.  Apical  system,  X  1|. 

241 


U    S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV     PLATE  XIII 


CRETACEOUS    ECHINOIDEA. 


PLATE   XIII. 

Salenia  tumidula  Clark  Cp.  50). 
Acad.  Nat.  Sci.  Philadelphia  1448,  tjrpe. 


Figure  la.  Upper  surface  of  the  test,  X  2. 
lb.  Under  surface  of  the  test,  X  2. 
Ic.  Lateral  surface  of  the  test,  X  2. 
Id.  Interambulacrum,  X  5. 
le.  Single  plate  of  same,  X  8. 
If.   Portion  of  ambulacrum,  X  10. 
Ig.  Apical  system,  X  IJ. 
Ih.  Genital  plate  of  same,  X  G. 
li.   Peristome,  X  3. 
Ij.   Tubercle,  X  10. 


Salenia  bellula  Clark  (p.  51). 
Acad.  Nat.  Sci.  Philadelphia  1446,  type. 


Figure  2a.  Upper  surface  of  the  test,  X  2. 
2b.  Under  surface  of  the  test.  X  2, 
2c.  Lateral  surface  of  the  test,  X  2. 
2d.  Three  interambulacral  plates,  X  6. 
2e.  Three  ambulacral  plates,  X  10. 
2f.    Apical  disk  enlarged. 
2g.  Tubercle,  X  10. 
242 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV    PLATE  XIV 


Ic 


uiy 


^. 


2a 


,»;:«^3sfE5»,  ^ 


3c 


3a 


3b 


CRETACEOUS    ECHINOIDEA. 


PLATE   XIV. 

Salenia  texana  Credncr  (p.  49). 
Johns  Hopkins  ITniv.  T  3003,  specimen  B. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 


Hypodiadema  elegans  Clark,  n.  sp.  (p.  52). 

U.  S.  Nat.  Mus.  31196,  type. 
Figure  2a.  LTpper  surface  of  the  test. 
2b.  Lateral  surface  of  the  test. 

GoNioPYGUs  ziTTELi  Clark  (]i.  52). 

U.  S.  Nat.  Mus.  12234,  type. 
Figure  3a.  Upper  sm'face  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 

243 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XV 


~%?s 


lb 


If 


le 


o 


O 


/ 

/{o? 

'■ •■■  / 

Q          O 

D 

Q  ; 

■■■ ■'  -  / 

"o      o 

O; 


O. 


o 


o 


■o 


o 


o 


o 


o 


G 


_/^., 


Ic 


Ih 


CRETACEOUS    ECHINOIDEA. 


PLATE   XV. 

GoNiOPYGUS  ziTTELi  Clark  (p.  52) 
U.  S.  Nat,  Mus.  12234,  type. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  same. 
Ic.  Interambulacrum,  X  3. 
Id.  Ambulacrum,  X  3. 
le.  Side  of  tubercle,  X  10. 
If.    Apical  system,  X  4. 
Ig.  Portion  of  interambulacrum,  X  4. 
Ih.  Lower  portion  of  ambulacrum,  X  10. 
244 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XVI 


le 


X 


V 


la 


2a 


CRETACEOUS    ECHINOIDEA. 


PLATE   XVI. 

Leptarbacia  argutus  Clark,  n.  sp.  (p.  53). 

Johns  Hopkins  Univ.  T  3004,  type. 

Figure  la.  Upper  surface  of  the  test, 
lb.  Lateral  surface  of  the  test. 
Ic.  Apical  system,  X  8. 
1(1.  Portion  of  ambulacrum,  X  8. 
le.  Portion  of  ambulacrum,  X  15. 
If.    Portion  of  interambulacrum,  X  4. 

Orthopsis  planxjlata  Clark,  n.  sp.  (p.  54). 

Johns  Hopkins  Univ.  7300.5,  type. 

Figure  2a.  Upper  and  lower  surfaces  of  two  forms. 
2b.  Lateral  surface  of  the  test. 
2c.  Portion  of  ambulacrum,  X  6. 

39800°— 15 18  245 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XVII 


lb 


la 


CRETACEOUS    ECHINOIDEA. 


PLATE   XVII. 

Orthopsis  occidentalis  Cragin  (p.  54). 
Geol.  Survey  Texas,  type. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Ambulacrum,  X  3. 
le.  Portion  of  ambulacrum,  X  6. 
If.    Portion  of  interambulacrum,  X  3. 
Ig.  Portion  of  apical  system,  X  4. 
246 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XVIII 


"«^ 


2a 


Ic 


2c 


Vi  ---^^ 


Ih 


Id 


2f 


2e 


CRETACEOUS    ECHINOIDEA. 


PLATE  XVIII. 

PSEUDODIADEMA    TEXANUM    (Roenicr)   (p.  55). 


U.  S.  Nat.  Mus.  31197. 

FiouKE  la.  Upper  surface  of  the  test,  X  2. 
lb.  Lower  surface  of  the  same,  X  2. 
Ic.  Lateral  surface  of  the  same,  X  2. 
Id.  Interambuhicrum,  X  4. 
le.  Ambulacrum,  X  4. 
If.   Three  interambulacral  plates,  X  8. 
Ig.  Tubercle,  X  12. 
Ih.  Portion  of  interambulacrum,  X  S. 
li.    Portion  of  ambulacrum,  X  8. 

Heterodiadema  ornatum  Clark,  n.  sp.  (p.  56). 
Johns  Hopkins  Univ.  T  SOOii,  type. 

Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Portion  of  ambulacrum,  X  10. 
2e.  Portion  of  interambulacrum,  X  10. 
2f.   Lateral  view  of  tubercle,  X  20. 

247 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XIX 


la 


If 


3a 


CRETACEOUS    ECHINOIDEA. 


PLATE   XIX. 

PSEUDODIADEMA  DIATKETUM  (Mortoil)    (p.  5(j). 
Acad.  Nat.  Sci.  Philadelphia  1471,  type. 


Figure  la.  Lower  surface  of  the  test. 
lb.  Lateral  view  of  the  test. 
Ic.  Two  interambulacral  plates,  X  5. 
Id.  Tlvree  ambulacral  plates,  X  8. 
le.  Same,  X  8. 
If.  Tubercle,  X  8. 


Cyphosoma  niLLi  Clark  (p.  59). 
U.  S.  Nat.  Mus.  8311,  type. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Upper  portion  of  an  ambulacrum,  X  5. 
2e.  Three  plates  of  the  same,  X  8. 
2f.   Tliree  interambulacral  plates,  X  4. 
22.  Tubercle. 


CoPTOsoMA  sPECiosuM  Clark  (p.  61). 

Acad.  Nat.  Sci.  I'hihidelphia  1468,  type. 


Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Upper  portion  of  an  interambulacrum,  X  4. 
3e.  Three  plates  of  the  same,  X  5. 
3f.  Three  plates  of  ambulacrum,  X  4. 
3g.  Same,  X  4. 
3h.  Tubercle,  X  10. 
248 


U-  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XX 


CRETACEOUS    ECHINOIDEA. 


PLATE   XX. 

CoTTALDiA  ROTULA  Clark,  n.  sp.   (p.  57). 

Johns  Hopkins  Univ.  T  3007,  type. 

Figure  la.  Side  nf  test  of  large  specimen, 
lb.  Side  of  test  of  small  specimen. 
Ic.  Portion  of  ambulacrum,  X  10. 
Id.  Portion  (if  interamljulacrum,   X  10. 

DiPLOPODIA  TAFFI  Ciagiii    (p.   58). 

Geol.  Survey  Texas,  type. 

Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Portion  of  ambulacrum,   X  5. 
2e.  Portion  of  interambulacrum,   X  5. 

DiPLOPODIA   STREERUVITZI  Ciagiii    (p.    58). 
Geol.  Survey  Texa.s,  type. 

Figure  .3a.  Upper  surface  of  the  test. 
3b.  Portion  of  ambulacra,   X  8. 
3c.  Portion  of  interambulacrum,   X  8. 

249 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXI 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXI. 

Cyphosoma  texanum  Roemcr  (p.  60). 
U.  S.  Nat.  Mus.  9838. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Tubercle,   X  10. 
le.  Ambulacrum,   X  3. 
If.  Portion  of  interambulacrum,   X  3. 
Ig.  Portion  of  amljulacrum,   X  8. 

Cyphosoma  volanum  Cragin  (p.  61). 

Geol.  Survey  Texas,  type,  specimen  A. 

Figure  2a.  Upper  surface  of  the  test,  X  2. 
2b.  Lower  surface  of  the  test,  X  2. 

Cyphosoma  volanum  Cragin  (p.  61). 
Geol.  Survey  Texas,  type,  specimen  B. 
Figure  3.  Upper  surface  of  the  test. 
250 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXII 


lb 


2i 


2d 


^.-sjm^s. 


2c 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXII. 

COPTOSOMA  MORTONI   (De  Loi'iol)    (p.   62). 

Collection  P.  de  Loriol,  type. 

Figure  la.  Upper  surface  of  the  test. 
lb.  Lateral  surface  of  the  test. 
Ic.  Three  arabulacral  plates,   X  8. 
Id.  Interambulacrum,   X  3. 
le.  Three  interambulacral  plates,   X  6. 

PsAMMECHiNUs  ciNGULATUS  Clark   (p.  63). 

Acad.  Nat.  Sci.  Philadelphia  1467,  type. 

Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  view  of  the  test. 
2d.  Interambulacrum,  X  5. 
2e.  Three  plates  of  the  same  X  8. 
2f.    Ambulacrum,   X  5. 
2g.  Four  plates  of  the  same,   X  8. 
2h.  Peristome,   X  2. 
2i.    Tubercle,   X  20. 

251 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   XXIII 


CRETACEOUS    ECHINOIDEA. 


PLATE  XXIII. 

Pedinopsis  symmetrica  (Cragin)  (p.  64). 
Geol.  Survey  Texas,  type. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.   Lateral  surface  of  the  test. 
Id.  Apical  system,  X  5. 
le.   Ambulacrum,  X  3. 
If.    Portion  of  ambulacrum,  X  8. 
Ig.   Interambulacrum,  X  3. 
Ih.  Portion  of  interambulacrum,  X  8. 
252 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXIV 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXIV. 

Pedinopsis  pondi  Clark  (p.  65). 
Johns  Hopkins  Univ.  T  3008,  type. 

Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  view  of  the  test. 
Id.    Four  ambulacral  plates,  X  •!• 
le.  Four  interambulacral  plates,  X  2. 

BoTRioPYGUs  ALABAMENSis  Clark   (p.  68). 

Acad.  Nat.  Sci.  Philadelphia,  type. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.    Lateral  surface  of  the  test. 

2d.  Portion  of  an  ambulacrum  at  base  of  petaloidal  region,  X  3. 
2e.    Same  in  center  of  petaloidal  region,  X  6. 
2f.   An  interambulacral  plate,  X  3. 

39800°— 15 19  253 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXV 


la 


2a 


3b 


2b 


2e 


3c 


3a 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXV. 

MiCEOPsis  LiNEATUs  Clark,  n.  sp.   (j).  63). 

U.  S.  Nat.  Mus.  31198,  type. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.   Lateral  surface  of  the  test. 


HoLECTYPUs  PLANATUS  Roemer   (p.  65). 

TJ.  S.  Nat.  Mus.  12236,  figured  specimen  A. 

Figure  2a.  Upper  surface  of  the  test  restored. 
2b .  Lower  surface  of  the  test  restored. 
2c.  Lateral  surface  of  the  test  restored. 
2d.  Two  interambulacral  plates,  X  3. 
2e.  Portion  of  the  ambulacrum,  X  5. 
2f.    Apical  system,  X  5. 

HoLECTYPus  PLANATUS  Roeiuer  (p.  65). 

U.  S.  Nat.  Mus.  1223G,  figured  specimen  B. 
Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.    Lateral  surface  of  the  test. 

HoLECTYPUS  PLANATUS  Roemer  (p.  65). 

Johns  Hopkins  Univ.  T  3008,  figured  specimen  D. 

Figure  4.  Lateral  surface  of  the  test. 
254 


U.  S.  GEOLOGICAL  SURVeV 


Monograph  liv    plate  xxvi 


la 


le 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXVI. 

HoLECTYPUS  PLANATUS  Koempr  (p.  65). 

Gecil.  Survey  Texas,  figured  specimeu  C. 

Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  AjJical  system,  X  5. 
Id.  Portion  of  ambulacrum,  X  3. 
le.  Portion  of  interambulacrum,  X  3. 

255 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXVII 


Is 


.ly 


Hl5 
ij 


li 


3a 


=?*'  "i^o  5*^0 


Ih 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXVII. 

Pyrina  parryi  Hall  (p.  67). 
IT.  S.  Nat.  Mus.  9854. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test, 
le.  Portion  of  ambulacrum,  X  5. 
If.  Portion  of  ambulacrum,  X  1. 
Ig.  Two  interambulacral  plates,  X  3. 
Ih.  Portion  of  interambulacral  plate, 
li.  Apical  system. 
Ij.  Portion  of  madreporite. 


EcHiNOBRissus  ANGUSTATUS  Clark,  n.  sp.  (p.  69). 

Johns  Hopkins  Univ.  T  3009,  type. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 


Cassidulus  coNOiDEiTs  Clark,  n.  sp.  (p.  80). 
U.  S.  Nat.  Mus.  31199,  type. 


Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 
256 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   XXVIII 


Ig 


2d 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXVIII. 

EcHiNOBRissus  EXPANsus  Clark  (p.  60). 

Acad.  Nat.  Sci.  Philadelphia  1465,  type. 

Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test, 
le.  An  interambulacral  plate,  X  3. 

If.  Portion  of  the  petaloidal  region  of  the  right  anterolateral  ambulacrum,  X  8 
Ig.  Apical  system,  X  5. 

EcHiNOBRissus  TEXANUs  Clark  (p.  70). 

U.  S.  Nat.  Mus.  20266,  type. 
FicjuRE  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 

2e.  Portion  of  the  right  anterolateral  ambulacrum,  X  10. 
2f.  Pour  interambulacral  plates,  X  5. 

Trematofygus  cruciferus  (Morton)  (p.  71). 

Acad.  Nat.  Sci.  Philadelphia  1464,  type. 


Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 


257 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXIX 


le 


C^::: 


& 


^ 


Ic 


^^>*yk, 


■'    Id  ''■'■ 


If 


2c 


•m 


2b 


2e 


4c 


4d 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXIX. 

Teematopygus  crucifer  (Morton)  (p.  71). 

Acad.  Nat.  Sci.  Philadelphia  1464,  type. 

Figure  la.  Posterior  surface  of  the  test. 

lb.  Lower  portion  of  the  petaloidal  region  of  the  right  posterolateral  ambulacrum,  X 5. 

Ic.  Several  plates  of  the  same,  X  10. 

Id.  Apical  system,  X  5. 

le.  Tubercle  from  above,  X  20. 

If.  Lateral  view  of  the  same,  X  20. 

Catopygus  oviformis  Conrad  (p.  72). 
Acad.  Nat.  Sci.  Philadelphia  1477,  type. 

Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 
2e.  Portion  of  right  posterolateral  amliulacruiii,  X  3. 
2f .  Several  plates  of  the  same,  X  10. 

Catopygus  pusillus  Clark  (p.  73). 

U.  S.  Nat.  Mus.  2210,  type. 


Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 


Catopygus  williamsi  Clark  (p.  73). 
Johns  Hopkins  Univ.  T  3010,  type. 


Figure  4a.  Upper  surface  of  the  test. 
4b.  Lower  surface  of  the  test. 
4c.  Lateral  surface  of  the  test. 
4d.  Posterior  surface  of  the  test. 
258 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XXX 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXX. 

Gassidulus  floreai.is  (Morton)  (p.  74). 
Acad.  Nat.  Sci.  Philadelphia  149.5,  type. 

Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test, 
le.  Right  posterolateral  ambulacrum,  X  3. 
If.  Several  plates  in  the  petaloidal  region  of  the  same,  X  8. 
Ig.  Same,  lower  surface,  X  8- 
Ih.  Posterior  interambulacrum,  X  2. 
li.  Single  plate,  X  -I- 
Ij.  Apical  system,  X  5. 
Ik.  Tubercle  from  above,  X  20. 
11.    Lateral  view  of  the  same,  X  20. 

Gassidulus  ^quoreus  Morton  (p.  75). 

Acad.  Nat.  Sci.  Philadelphia  1475,  type. 

Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 
2e.  Anterior  ambulacrum,  X  2. 
2f.  Several  plates,  petaloidal  region  of  the  same,  X  8. 
2g.  Same,  oral  region,  X  8. 
2h.  Apical  system,  X  5. 
2i.  Diagram  showing  the  arrangement  of  the  plates  about  the  peristomial  opening,  X  2. 

259 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XXXI 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXI. 

Cassidulus  micrococcus  Gabb  (p.  76). 

Acad.  Nat.  Sci.  Philadelphia  1480,  tyiie. 

Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  iuirface  of  the  test. 

le.  Anterior  ambulacrum  at  the  base  of  the  petaloidal  region,  X  2. 
If.  Several  plates  in  petaloidal  region  of  the  anterior  ambulacrum,  X  8. 
Ig.  Oral  portion  of  an  ambulacrum,  X  8. 
Ih.  Apicalsystem,  X  o. 
li.  Surface  of  an  interambulacral  plate,  X  20. 

Cassidulus  subquadratus  Conrad  (p.  77). 

U.  S.  Nat.  Mus.  31200. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 

2e.  Lower  portion  of  the  petaloidal  region  of  the  right  anterolateral  ambulacrum,  X  2. 
2f .   Oral  portion  of  an  ambulacrum,  X  5. 
2g.  Apical  system,  X  8. 
260 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XXXII 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXII. 

Cassidulus  subconicus  Clark  (j).  77). 

U.  S.  Nat.  Mus.  20264,  type. 
Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  siu'face  of  the  test. 
le.  Anterior  ambulacrum,  X  2. 
If.  Several  plates  of  the  petaloidal  jwrtion,  X  8. 
Ig.  Same,  phylloidal  portion,  X  6. 

Ih.  Diagram  showing  the  arrangement  of  the  plates  around  the  peristomial  o])ening,  X  2. 
li.  Interambulacral  plate,  X  5. 
Ik.  Apical  system,  X  5. 

CASsiDm.us  PORRECTUS  Clark  (p.  78). 

U.  S.  Nat.  Mus.  21890,  type. 
Figure  2a.  Upper  surface  of  the  test 

2b.  Anterior  ambulacrum,  X  1^. 

39800°— 15 20  261 


U,  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXXIII 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXIII. 

Cassidxilus  poreectus  C^lark  (p.  78). 
U.  R.  Nat.  Mus.  21890,  type. 


Figure  la.  Posterior  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Lower  portion  of  petaloidal  region,  X  5. 
le.  Central  portion  of  the  same,  X  5- 
If.    Three  interambulacral  plates,  X  2. 


Cassidulus  stantoni  Clark  (p.  79). 
U.  S.  Nat.  Mus.  20260,  type. 


Figure  2a.  Upper  surface  of  the  test,  X  2. 
2b.  Lower  svuface  of  the  test,  X  2. 
2c.  Lateral  surface  of  the  test,  X  2. 
2d.  Posterior  surface  of  the  test,  X  2. 
262 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXXIV 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXIV. 

Cassidulus  intermedius  Slocum  (p.  79). 

Field  Mus.  P  10346,  type. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Posterior  surface  of  the  test. 
Id.  Lateral  surface  of  the  test. 

le.  Portion  of  left  anterior  ambulacrum  at  base  of  petaloidal  region,  X  5. 
If.    Same,  phylloidal  portion,  X  5. 

Cassldulus  hemisphericus  Slocum  (p.  SO). 

Field  Mus.  P.  10347,  type. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lateral  surface  of  the  test. 
2c.  Portion  of  anterior  ambulacrum  at  base  of  petaloidal  region,  X  5. 

HoLASTER  SIMPLEX  Shuiiiard  (p.  85). 

U.  S.  Nat.  Mus.  8382,  figiu-ed  specimen  A. 

Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 


263 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXXV 


1^3^=^^^ 


±j^ 


t 


.-^.-'^l^-.'iJJ:.  :■ 


Ih 


If    '0 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXV. 


Ananchytes  ovalis  Clark  (p.  81). 


Figure  la. 
lb. 
Ic, 
Id. 
le. 
If. 

Ig- 
Ih. 


Johns  Hopkins  Univ.  T  3011,  type. 


Upper  surface  of  the  test. 
Lower  surface  of  the  test. 
Lateral  surface  of  the  test. 
Anterior  surface  of  the  test. 
Posterior  surface  of  the  test. 
Apical  system,  X  5. 
Ambulacral  plates,  X  5. 
Interambulacral  plates,  X  3. 


Ananchytes  texana  Cragin  (p.  82). 
Geol.  Survey  Texas,  type. 


Figure  2a.  Lower  surface  of  the  test. 

2b.  Portion  of  ambulacrum,  X  2. 
2c.  Portion  of  interambulacrum,  X 
264 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXXVI 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXVI. 

Ananchytes  texana  Cragin  (p.  82). 

Geol.  Survey  Texas,  type. 
Figure  la.  Anterior  surface  of  the  test. 
lb.  Lateral  surface  of  the  test. 

Cardiaster  cinctus  (Morton)  (p.  83). 

Acad.  Nat.  Sci.  Philadelphia  1485,  type. 

Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Anterior  surface  of  the  test. 
2e.  Posterior  surface  of  the  test. 

2f.  Central  portion  of  the  petaloidal  region  of  an  ambulacral  area,  X  5. 
2g.  Basal  portion  of  same,  X  4. 
2h.  Apical  system,  X  5. 

Cakdiastek  smocki  Clark  (p.  84). 

Geol.  Survey  New  Jersey,  type. 
Figure  3a.  Upper  surface  of  the  te-st. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 

265 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XXXVII 


Id 


le 


^  .'.  .':■■{;.■■.■.'■  ::>:*,■■.  ■/■:"-v.;  ■-"-;.■ 


vyVr^C  . 


.■-*.■■ 


If 


;^  j?:v:..;.,,;vr:-i«-t/;r'  / 


Ih 


"^ 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXVII. 

Cabdiaster  curtus  Clark,  n.  up.  (p.  84). 
U.  S.  Nat.  Mus.  31201,  type. 


Figure  la.  Upper  surface  of  the  te.st. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Apical  system,  X  10. 
le.  Portion  of  ambulacrum,  X  10. 
If.  Several  plates  of  same,  X  15. 
Ig.  Portion  of  interambulacrum,  X  10. 
Ih.  Interambulacral  plate,  X  15. 
266 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE    XXXVIII 


Ig 


<giM 


If 


Ih 


Ic 


i^ 


le 


lb 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXVIII. 

HoLASTER  SIMPLEX  Shumard  (p.  8.5). 
U.  S.  Nat.  Mus.  8382,  figured  si)eciraen  A. 


Figure  la.  Lateral  surface  of  the  test. 

lb.  Lateral  surface  of  the  teat  restored. 

Ic.  Posterior  siu'face  of  the  test. 

Id.  Portion  of  the  ambulacrum,  X  3. 

le.  Portion  of  the  ambulacrum,  X  3. 

If.   Tubercle,  X  10. 

Ig.  Tubercle,  X  10. 

Ih.  Interambulacral  plate,  X  3. 

li.   Right  anterolateral  ambulacrum,  X 

Ij.   Apical  system,  X  3. 


267 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XXXIX 


'v^i©; 


If 


le 


Id 


'^■■'■f^'--^tiiiip-^(--^''^  '/^ 


Ig 


2e 


2g 


CRETACEOUS    ECHINOIDEA. 


PLATE   XXXIX. 

HoLASTER  SIMPLEX  Shiimartl  (p.  85). 
Geol.  Survey  Texas,  figured  specimen  B. 

Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  siu'face  of  the  test. 
Id.  Anterior  siu-face  of  the  test, 
le.   Apical  system,  X  4. 
If.    Portion  of  ambulacrum,  X  10. 
Ig.  Tliree  interambulacral  plates,  X  5- 

Enallaster  texanxjs  (Roemer)  (p.  86). 

U.  S.  Nat.  Mus.  9857. 
Figure  2a.  Upper  view  of  the  test. 
2b.  Lower  view  of  the  teat. 
2c.  Posterior  view  of  the  test. 
2d.  Posterior  view  of  the  test. 

2e.  Portion  of  the  petaloidal  region  of  the  right  anterolateral  araljulacriim,  X  10. 
2f.   Portion  of  the  anterior  ambulacrum,  X  10. 
2g.  Apical  system,  X  6. 

268 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XL 


lb 


la 


'/,••. 


li 


Id 


"->;?ffl 


11 


Ik 


Ic 


CRETACEOUS    ECHINOIDEA. 


PLATE   XL. 

Enallaster  obliquatus  Clark  (p.  87). 

U.  S.  Nat.  Mus.  12237,  type. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  view  of  the  test. 
Id.  Posterior  view  of  the  test. 

le.  Portion  of  the  petaloidal  region  of  the  anterior  amlnilacrum,  X  8. 
If.    Same,  left  anterior  ambulacrum,  X  8. 
Ig.  Second  plate  of  the  same  from  the  mouth  opening,  X  8. 
Ih.  Diagram  showing  arrangement  of  plates  about  the  mouth  opening,  X  3. 
li.   Apical  system,  X  6. 
Ik.  Tubercle  from  above,  X  10. 
11.    I,ateral  view  of  the  same,  X  10. 

269 
39.S<H)°— li". 21 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XLI 


Ic 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLI. 

Hemiaster  elegans  Shumard  (p.  88). 
U.  S.  Nat.  Mus.  21887. 


Figure  la.  Upper  surface  of  the  test. 
lb.  I^ateral  surface  of  the  test. 
Ic.  Posterior  surface  of  the  test. 
270 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XLII 


Ic 


le 


lb 


la 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLII. 

Hemiaster  elegans  Shumard  (p.  SS). 

Geol.  Survey  Texas. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id .  Posterior  surface  of  the  test, 
le.  Apical  system,  X  5. 
If.   Portion  of  anterior  ambulacrum,  X  5. 
Ig.  Same. 
Ih.  Portion  of  interambulacrum,  X  5. 

271 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XLIII 


If 


le 


2c 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLIII. 

Hemiaster  elegans  Shumard  (p.  88). 

U.  S.  Nat.  Mus.  21887. 
Figure  la.  Lowpr  portion  of  the  test. 

lb.  Middle  portii.in  of  tlie  petaloidal  region  of  the  anterior  ambulacrum,  X  5- 

Ic.  Same,  left  anterolateral  ambulacrum,  X  5. 

Id.  Two  interambulacral  plates,  X  3. 

le.  Apical  system,  X  5. 

If.   Upper  portion  of  the  anterior  ambulacrum,  X  3. 

Hemiaster  ■\vhitei  Clark  (p.  89). 

U.  S.  Nat.  Mus.  9732  type. 
Figure  2a.  Upper  surface  of  the  test. 

2b .  Posterior  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
272 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XLIV 


Ih 


°-  '  '?'■  'Q'-'I*^'''':;^'  :'  .5.'    .-■"-■^o'-O."  ! " 


le 


If 


lb 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLIV. 

Hemiastee  whitei  Clark  (p.  89). 

U.  S.  Nat.  Mus.  9732,  type. 
Figure  la.  Lower  surface  of  the  test. 

lb.  Right  anterolateral  interambulacnim,  X  3. 

Ic.  Lower  portion  of  the  petaloidal  region  of  the  right  anterolateral  ambulacrum,  X  8. 
Id.  Several  plates  of  the  petaloidal  region  of  the  left  anterolateral  ambulacrum,  X  8. 
le.  Peristomial  opening,  with  surrounding  ambulacral  and  interambulacral  plates,  X  3. 
If.   Apical  system,  X  5. 
Ig.  Left  anterolateral  ambulacrum ,  X  3. 

Ih.  Diagram  showing  the  arrangement  of  the  plates  in  the  apical  system  and  bordering  areas,  X  3. 

273 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XLV 


la 


lb 


Ic 


1^' 


2c 


2d 


2a 


s^ 


\-  r' 


r' 


2e 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLV. 

Hemiaster  whitei  Clark  (p.  89). 


U.  S.  Nat.  Mus.  31202. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lateral  surface  of  the  test. 
le.  Posterior  surface  of  the  test. 


Hemiaster  whitei  Clark  (p.  89). 

U.  S.  Nat.  Mus.  4544. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 
2e.  Apical  system,  X  5. 
2f.    Portion  of  ambulacrum,  X  8, 
274 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XLVI 


Id 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLVI. 

Hemiaster  bexari  Clark,  n.  sp.  (p.  89). 

U.  S.  Nat.  Mua.  8330,  type. 
Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 
le.  Portion  of  atabiilacrum,  X  5. 

Hemiaster  comanchei  Clark,  n.  sp.  (p.  90). 

Johns  Hopkins  Univ.  T  3012,  type. 
Figure  2a.  LTpper  surface  of  tlie  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 

275 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XLVII 


Ic 


Id 


If 


lb 


le 


2b 


2d 


2i 


2gr 


2c 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLVII. 
Hemiaster  dalli  Clark  (p.  90). 

U.  S.  Nat.  Mus.  19114,  type. 
Figure  la.  Upper  surface  of  the  test. 

lb.  Upper  surface  of  the  test  restored. 

Ic.  Lower  surface  of  the  test. 

Id.  Lateral  surface  of  the  test. 

le.  Posterior  surface  of  the  test. 

If.    Several  plates  from  the  petaloidal  portion  of  the  left  anterolateral  ambulacrum ,  X  5. 

Hemiaster  calvini  (lark  (p.  90). 

U.  8.  Nat.  Mus.  12241,  type. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  \'iew  of  the  test. 
2(1.  Posterior  view  of  the  test. 

2e.  Several  plates  from  the  petaloidal  region  of  the  right  posterolateral  ambulacrum,  X  5. 
2f.    Same,  lower  portion  of  petaloidal  region,  X  5. 
2g.  Several  plates  from  anterior  ambulacrum,  X  5. 
2h.  Interambulacral  plate,  X  3. 
2i.   Apical  system,  X  5. 
276 


U,  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LtV      PLATE   XLVIII 


^Vtv  V*--'  ^-x  y*  \^v'^y  ■■ 

Ik 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLVIII. 

Hemiaster  parastatus  (Morton)  (p.  92). 
Acad.  Nat.  Sci.  Philadelphia  1487,  type. 

Figure    la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 
le.  Anterior  ambulacrum,  X  2. 
If.  Portion  of  petaloidal  region  of  the  same,  X  8. 
Ig.  Portion  of  basal  region,  ditto,  X  5. 

Ih.  Several  plates  from  the  petaloidal  region  of  the  right  anterolateral  ambulacrum,  X  5. 
li.  Three  interambulacral  plates,  with  fasciole,  X  3. 
Ik.  Portion  of  fasciole,  X  10. 
11.  Tubercle  from  the  side,  X  20. 
Im.  Same  from  above,  X  20. 
In.  Apical  system,  X  5. 

Hemiaster  stella  (Morton)  (p.  93). 

U.  S.  Nat.  Mus.  2208. 
Figure  2a.  Upper  surface  of  the  test. 
2b .  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 

Hemiaster  ungula  (Morton)  (p.  93). 

Acad.  Nat.  Sci.  Philadelphia  1.503,  type. 

Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 

3e.  Portion  of  the  petaloidal  region  of  the  right  anterolateral  ambulacrum,  X  8. 
3f .   Same,  anterior  ambulacrum,  X  8. 
3g.  Apical  system,  X  5. 

39S(K)°— 15 22  277 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XLIX 


■.■'-1^.    •   i 


Ij 


li 


la 


Ih 


2d 


2c 


CRETACEOUS    ECHINOIDEA. 


PLATE   XLIX. 

Hemiaster  texanus  Roemer  (p.  94). 

Johns  Hopkins  Univ.  T  3013. 
Figure  la.  Upper  surface  of  the  test. 

lb.  Lower  surface  of  the  test  restored,  X  IJ- 

Ic.  Lower  surface  of  the  test,  ditto,  X  IJ. 

Id.  Lateral  surface  of  the  test,  X  IJ- 

le.  Posterior  surface  of  the  test,  ditto,  X  11- 

If.   Several  plates  from  the  petaloidal  region  of  the  riglit  jiosterolateral  ambuhicrum,  X  8 

Ig.  Same,  anterior  ambulacrum,  X  8. 

Ih.  Apical  system,  X  5. 

li.   Lateral  view  of  a  tubercle,  X  20. 

Ij.   Tubercle  from  above,  X  20. 

Hemiaster  humphreysanus  Meek  and  Ilayden  (p.  95). 

U.  S.  Nat.  Mus.  331,  type. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test, 
2d.  Posterior  surface  of  the  test. 

2e.  Several  plates  from  the  petaloidal  portion  of  the  left  anterolateral  ambulacrum,  X  8. 
2f .   Several  plates  from  tlie  petaloidal  portion  of  the  anterior  ambulacrum,  X  8. 
278 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  U 


CRETACEOUS    ECHINOIDEA. 


PLATE   L. 

Hemiastek  californicus  Clark  (p.  96). 
U.  S.  Nat.  Mus.  31203,  type. 


Figure  la.  Upper  surface  of  the  test. 

lb.  Upper  surface  of  the  test,  restored. 
Ic.  Lower  surface  of  the  test. 
Id.  Lateral  surface  of  the  test. 


Hemiaster  beecheri  Clark,  n.  sp.  (p.  96). 
Peabody  Museum,  Yale  University,  1863,  type. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 


Hemiaster  lacunosus  Slocuni  (p.  97). 
U.  S.  Nat.  Mus.  31204,  type. 


Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 


279 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE    LI 


CRETACEOUS    ECHINOIDEA. 


PLATE   LI. 

Hemiaster  lacunosus   Slocum    (p.  97). 

Field  Mus.  P  10342,  type. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test, 
le.  Apical  system,  X  10. 
If.   Portion  of  anterior  ambulacrum,  X  '■ 
Ig.  Same,  petaloidal  region,  X  8. 
Ih.  Lateral  view  of  tubercle,  X  20. 
li.   Tubercle  from  above,  X  20. 
280 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   Lll 


la 


2a 


2b 


CRETACEOUS    ECHINOIDEA. 


PLATE   LII. 

IlEMiAiSTEK  KUMMET.i  Clark  (p.  97). 

Geol.  Survey  New  Jersey,  type. 
Figure  la.  Upper  surface  of  the  test. 
lb .  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 

Hemiaster  welleri  Clark  (p.  98). 

Geol.  Survey  New  Jersey,  type. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 

281 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   Llll 


Ic 


Id 


Ih 


Ig 


■f^  ^.f'""^ 


:©■; 


©, 


■©. 


li 


la 


lb 


CRETACEOUS    ECHINOIDEA. 


PLATE   LIII. 

LiNTHiA  TUMiDULA  Clark  (p.  99). 

Am.  Mus.  Nat.  Hist.,  type. 
Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  sm-face  of  the  test. 
Id.  Posterior  surface  of  the  test, 
le.  Upper  portion  of  the  anterior  ambulacrum,  X  5. 

If.    Several  plates  from  the  petaloidal  region  of  the  left  posterolateral  ambulacrum,  X 
Ig.   Apical  system,  X  5. 
Ih.  Tubercle  from  the  side,  X  20. 
li.    Tubercle  from  above,  X  20. 

282 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LIV 


la 


If 


^•g-'wsr**^) 


^'W'f**.^*,^-,  ^^-^L.*\ 


'^. 


'*<»*7'=!»<5l?9  'a  ®  j 


CRETACEOUS    ECHINOIDEA. 


PLATE   LIV. 

LiNTHIA    VARIABILIS    SloCUm     (p.  99). 

Field  Mua.  P  10457,  type. 

Figure  la.  Upper  surface  of  the  test  (P  10457). 
lb.  Lower  surface  of  the  test  (P  10457). 
Ic.  Lateral  surface  of  the  test  (P  10457). 
Id.  Posterior  surface  of  the  test  (P  10457). 
le.  Upper  surface  of  the  test  (P  10457). 
If.    Lower  surface  of  the  test  (P  10457). 
Ig.  Lateral  surface  of  the  test  (P  10457). 
Ih.  Posterior  surface  of  the  test  (P  10457). 
li.    Apical  system,  X  10. 
Ik.  Portion  of  ambulacrum,  X  20. 
11.    Portion  of  ambulacrum,  X  8. 

283 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LV 


2b 


EOCENE    ECHINOIDEA. 


PLATE   LV. 

CiDAEis  MiTCHELLi  Emmoiis  (p.  113). 
Williams  College,  type. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 

CiDARis  CAROLiNENSis  Emmons  (p.  113). 

Williams  College,  type. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  siu^ace  of  the  test. 

CiDARis  PRATT!  Clark,  n.  sp.  (p.  114). 
U.  S.  Nat.  Mus.  164663,  type. 
Figure  3.  Portion  of  interambulacrum  with  adjoining  ambulacra. 

ClDARIS   MERRIAMI   Arnold  (p.  114). 

U.  S.  Nat.  Mus.  165438,  type. 
Figure  4.  Spine,  after  Arnold. 
284 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LVI 


EOCENE    ECHINOIDEA. 


PLATE   LVI. 

CCELOPLEUEUS    INFULATUS   (Morton)    (]).   117). 
Acad.  Nat.  Sci.  Pliiladelphia  1076. 


Figure  la.  Upper  surface  of  the  test,  X  2. 
lb.  Lateral  surface  of  the  test,  X  2. 
Ic.  Lower  surface  of  the  test,  X  2. 
Id.  L'^pper  portion  of  an  ambulacrum,  X  6. 
le.  Four  compound  plates  of  an  ambulacrum,  X  6. 
If.  Three  plates  of  an  interambulacrum,  X  6. 
Ig.  An  interambulacrum,  X  6. 
Ih.  Tubercle,  X  10. 
li.  Apical  system,  X  4. 


Orthechinus  pketiosus  Clark,  n.  sj).  (p.  118). 
IT.  S.  Nat.  Mus.  146455,  type. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  I^ateral  surface  of  the  test. 


Figure  ;^.  Spines. 

30800°— 15 23 


Echinus  (?)  sp.  (p.  118). 
Johns  Hopkins  Univ.  T  2000. 


2S5 


U.  S.  QEOLOQICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LVII 


EOCENE    ECHINOIDEA. 


PLATE   LVII. 

EcHiNOCYAMUs  iiuxLEYANUs  Moyer  (p.  119). 
Johns  Hopkins  Univ.  T  200G. 


Figure  la.  Upper  surface  of  the  test,  X  4. 

lb.  Lower  surface  of  the  test,  X  4. 

Ic.  Lateral  surface  of  the  test,  X  4. 

Id.  Posterior  surface  of  the  test,  X  4. 


EcHiNOCYAMUs  TEXANUs  Twitchell,  n.  sp.  (p.  120). 
Johns  Hopkins  Univ.  T  2002,  type. 


Figure  2a.  Upper  surface  of  the  test,  X  2. 
2b.  Lower  surface  of  the  test,  X  2. 
2c.  Lateral  surface  of  the  test,  X  2. 
2d.  Posterior  surface  of  tlie  test,  X  2. 


FiBULARIA    MERIDIONALIS   (MeyOl)    (jl.   121). 
Johns  Hopkins  Univ.  T  2005. 


Figure  3a.  Upper  surface  of  the  test,  X  4J. 
3b.  Lower  surface  of  the  test,  X  4J. 
3c.  Lateral  surface  of  the  test,  X.  4i. 
3d.  Posterior  surface  of  the  test. 


SiSMONDiA  (?)  PLANA  Conrad  (p.  121). 

Acad.  Nat.  Sci.  Philadelphia  1080,  type. 


Figure  4a.  Upper  siwface  of  the  test. 
4b.  Lower  surface  of  the  test. 
4c.  Lateral  surface  of  the  test. 
4d.  Posterior  surface  of  the  test. 


Laganum  (?)  CRUSTULOiDES  (Mortoii)  (p.  122). 
Boston  Soc.  Nat.  Hist.  8802a,  specimen  A. 


Figure  5a.  Upper  surface  of  the  test. 
5b.  Lower  surface  of  the  test. 
5c.  Lateral  surface  of  the  test. 
5d.  Posterior  surface  of  the  test. 


Laganum  (?)  crustuloides  (Morton)  (p.  122). 
U.  S.  Nat.  Mus.  1G4744,  specimen  C. 


Figure  6a.  Upper  surface  of  the  test. 
6b.  Lower  surface  of  the  test. 
6c.  Lateral  surface  of  the  test. 
Gd.  Posterior  surface  of  the  teat. 
286 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LVIII 


Ic 


Id 


le 


Ib 


EOCENE    ECHINOIDEA. 


PLATE   LVIII. 
Periakchus  altus  Conrad  (p.  130). 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Detail  of  apical  system,  X  5. 
Id.  Posterior  surface  of  the  test. 
le.  Lateral  surface  of  the  test. 


Williams  College,  type. 


287 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LIX 


la 


Ic 


fi^^. 


Id 


r.'-'         ■'    'fX 


J-L 


<^??^ 


le 


*  ',»-^JB^5mihe ' 


EOCENE    ECHINOIDEA. 


A 


If 


PLATE   LIX. 

ScuTELLA  MississiPPiENSis  Twitchell,  n.  sp.  (p.  124). 
U.  S.  Nat.  Mu8.  137655,  specimen  A,  type. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Posterior  surface  of  the  test. 
Id.  Lateral  surface  of  the  test. 
le.  Apical  system,  X  6. 
If.   Part  of  the  ambulacra,  X  8. 


ScuTELLA  MISSISSIPPIENSIS  Twitcliell,  u.  sp.  (p.  124). 

U.  S.  Nat.  Mus.  137655a,  specimen  B. 


Figure  2.  Upper  surface  of  the  test. 
288 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LX 


Ic 


la 


lb 


Id 


2e 


'hill 


v^ 


2f 


EOCENE    ECHINOIDEA. 


PLATE   LX. 

ScuTELLA  TUOMEYi  Twitchell,  n.  sp.  (p.  125). 

U.  S.  Nat.  Mus.  137970,  type. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 

MORTONELLA    QUINQUEFARIA    (Say)    (p.   128). 

U.  S.  Nat.  Mus.  9500,  specimen  A. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Posterior  surface  of  the  test. 
2d.  Lateral  surface  of  the  test. 
2e.  Part  of  one  of  the  ambulacra,  X  4. 
2f.   Apical  system,  X  6. 

280 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LXI 


-—..X.  *\  If  ^# 
"~-^  ~■--^,'\l'.>*-• 


EOCENE    ECHINOIDEA. 


PLATE   LXI. 

MOETONELLA    QUINQUEFARIA    (Siiy)    (p.  128) 
Amherst  College,  specimen  B. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lateral  surface  of  the  test. 


Periarchus  lyelli  Conrad  (p.  L'il). 
Boston  Soc.  Nat.  Hist.  1553,  specimen  A. 


Figure  2a.  Upper  surface  of  tlio  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 
2e.  Part  of  one  of  the  ambulacra,  X  5J. 
2f.   Apical  system,  X  4. 
290 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  LXII 


EOCENE    ECHINOIDEA. 


PLATE   LXIl. 


Peeiaechtjs  lyelli  Conrad  (p.  131). 
Johns  Hopkins  Univ.  T  2003,  specimen  B. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.   Lateral  surface  of  the  test. 


Periarchus  lyelli  Conrad  (p.  131). 
Johns  Hopkins  Univ.  T  2004,  specimen  C. 


Figure  2a.   Upper  surface  of  the  test. 
2b.  Ijower  surface  of  the  test. 
2c .   Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 


Figure  3a. 
3b. 
3c. 
3d. 
3e. 
3f. 


Periarchus  prottjberans  Twitchell,  n.  sp.  (p.  133). 

U.  S.  Nat.  Mus.  164685,  type. 


Upper  surface  of  the  test. 
Lower  surface  of  the  test. 
Lateral  surface  of  the  test. 
Posterior  surface  of  the  test. 
Part  of  one  ambulacrum,  X  8- 
Apical  system,  X  8. 


291 


U.  S.  QEOLQQICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LXIII 


EOCENE    ECHINOIDEA. 


PLATE   LXIII. 

Periarchus  pileus-sinensis  Ilavc'iu'l  (p.  135). 

U.  S.  Nat.  Mus.  5133,  specimen  A. 


Figure  la.  Upper  surface  of  the  test, 

lb.  Lower  surface  of  the  test. 

Ic.  Lateral  surface  of  the  test. 

Id.  Posterior  surface  of  the  test, 

le.  Part  of  one  ambulacrum,  X  6. 


Peeiaechus  pileus-sinensis  Raveiipl  (p.  13.5). 
U.  S.  Nat.  Mus.  137791,  specimen  B. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.   Posterior  surface  of  the  test. 
2d.  Lateral  surface  of  the  test. 
292 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXIV 


Id 


Ic 


c 


EOCENE     ECHINOIDEA. 


PLATE   LXIV. 

SctttellaC?)  conradi  (Cotteau)  (p.  126). 
Acad.  Nat.  Sci.  Philadelphia  1081,  type. 


Figure  la.  Upper  surface  of  the  test, 

lb.  Lower  surface  of  the  test. 

Ic.  Lateral  surface  of  the  test. 

Id.  Posterior  surface  of  the  test. 

Clypeaster  rogersi  Mortoii  (p.  136). 

IT.  S.  Nat.  Mus.  137801,  specimen  A. 

Figure  2a.  Upper  surface  of  the  test. 

2b.  Lower  surface  of  the  test. 

2c.  Posterior  surface  of  the  the  test. 

2d.  Lateral  surface  of  the  test. 

Clypeaster  rogersi  Morton  (p.  136). 

U.  S.  Nat.  Mus.  155377,  specimen  B. 

Figure  3a.   Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 

39800°~15 24  293 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXV 


EOCENE    ECHINOIDEA. 


PLATE   LXV. 

ECHINANTHUS    GEORGIENSIS    Twitchell,  11.  Sp.    (p.   139). 

U.  S.  Nat.  Mus.  165683b,  type. 
Figure  la.   Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.   Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 

Cassidulus  californicus  F.  M.  Anderson  (p.  140). 

U.  S.  Nat.  Mus.  165664. 
Figure  2a.   Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 

Cassidulus  (Rhynchopygus  ?)  holmesi  Twitchell,  n.  sp.  (p.  140). 

Am.  Mus.  Nat.  Hist.,  type. 


Figure  3a.   Upper  surface  of  the  t«st. 
3b.  Lower  surface  of  the  test. 
3c.   Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 


Cassidulus  (Rhynchopygus)  lyelli  (Conrad)  (p.  141). 
Boston  Soc.  Nat.  Hist.  1552a. 


Figure  4a.  Upper  surface  of  the  test. 
4b.  Lower  surface  of  the  test. 
4c.   Posterior  surface  of  the  test. 
4d.  Lateral  surface  of  the  test. 


Cassidulus  (Rhynchopygus)  raveneli  Twdtchcll,  n.  sp.  (p.  142). 
Am.  Mus.  Nat.  Hist.,  specimen  A,  type. 


Figure  5a.  LTpper  surface  of  the  test. 
5b .  Lov/er  surface  of  tlie  test. 
5c.   I/ateral  surface  of  the  test. 
5d.  Posterior  surface  of  the  test. 
294 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXVI 


3a 


4c 


5a 


3d 


5b 


EOCENE    ECHINOIDEA. 


PLATE   LXVI. 

Cassidulus  (Rhynchopygus)  raveneli  T\satchell,  n.  sp.  (p.  142) 
Am.  Mus.  Nat.  Hist.,  specimen  B. 


Figure  la.  Upper  surface  of  the  test. 

lb.  Part  of  one  ambulacrum,  X  8. 
Ic.  Apical  system,  X  8. 


Cassidulus  (Rhynchopygus)  raveneli  Twitchell,  n.  sp.  (p.  142). 
Am.  Mus.  Nat.  Hist.,  specimen  C. 


Figure  2a.  Lower  surface  of  the  test. 
2b.  Part  of  floscelle,  X  4. 


Cassidulus  (Rhynchopygus?)  patelliformis  (Bouve)  (p.  143). 

Boston  Soc.  Nat.  Hist.  1558,  type. 


Figure  3a.  Upper  surface  of  the  test. 
3b .  Lower  surface  of  tlie  test. 
3c.  Posterior  surface  of  tlie  test. 
3d.  Lateral  surface  of  the  test. 


Cassidulus  (Rhynchopygus)  depressus  Twitchell,  n.  sp.  (p.  144). 

Boston  Soc.  Nat.  Hist.  1557a,  specimen  A,  type. 

Figure  4a.  LTpper  surt'ace  of  the  test. 

4b.  Lower  surface  of  the  test. 

4c.  Posterior  surface  of  the  test. 

4d.  Late/al  surface  of  the  test. 

4e.  Part  of  one  ambulacrum,  X  12. 

Cassidulus  (Rhynchopygus)  depressus  Twitchell,  n.  sp.  (p.  144). 

Boston  Soc.  Nat.  Hist.  1557b,  specimen  B. 

Figure  5a.  Lower  surface  of  the  test. 
5b.  Part  of  floscelle,  X  8. 

295 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LXVII 


2c 


^■^^^ 


2g 


Ic 


EOCENE    ECHINOIDEA. 


PLATE   LXVII. 

Cassidulus  (Pygokhynchus)  coneadi  Conrad  (p.  145). 

Acad.  Nat.  Sci.  Pliiladelpliia  1078,  probably  type. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Jjower  surface  of  the  test. 
Ic.  Posterior  surface  of  the  test. 
Id.  Lateral  surface  of  the  test. 
le.   Part  of  one  ambulacrum,  X  8. 
If.    Part  of  floscelle,  X  7. 


Cassidulus  (Pygokhynchus)  carolinensis  Twitchell,  n.  sp.  (p.  146). 
Johns  Ilopkins  Univ.  T  2004,  type. 


Figure  2a.   Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 
2e.  Part  of  floscelle,  X  5. 
2f.    Part  of  one  ambulacrum,  X  8^. 
2g.  Apical  system,  X  6. 
296 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXVIII 


2d 


If 


ie 


EOCENE    ECHINOIDEA. 


PLATE   LXVIII. 
Breynella  gregoryi  Twitchell,  n.  ap.  (p.  148). 


Am.  Mus.  Nat.  Hist.,  type. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.   Posterior  surface  of  the  test. 
Id.  Lateral  surface  of  the  test. 
le.  Apical  system,  X  6. 
If.    Part  of  ambulacra. 


EcHiNOLAMPAS  APPENDicuLATUS  Emmons  (p.  149). 

U.  S.  Nat.  Mus.  138017. 


Figure  2a.   Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.   Posterior  surface  of  the  test. 
2d.  Lateral  surface  of  the  test. 
2e.   Part  of  fioscelle,  X  4. 
2f .    Apical  system,  X  5. 
2g.   Part  of  interambulacra. 
2h.  Part  of  ambulacra,  X  10. 


29T 


U.  S.  GEOLOQICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXIX 


EOCENE    ECHINOIDEA. 


PLATE   LXIX. 

Hemipatagus  argutus  Clark,  n.  sp.  (p.  150). 
U.  S.  Nat.  Mus.  141107,  type. 


Figure  la.  Upper  surface  of  the  test. 

lb .  Lower  surface  of  the  test. 

Ic.  Lateral  surface  of  the  test. 

Id.  Posterior  surface  of  the  test. 


Hemipatagus  subrostratus  Clark,  n.  sp.  (p.  151). 
U.  S.  Nat.  Mus.  164652,  type. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Anterior  surface  of  the  test. 


Schizaster  leco\tei  Merriam  (]).  151). 
Univ.  of  California ,  type. 


Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
298 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  LXX 


la 


EOCENE    ECHINOIDEA. 


PLATE   LXX. 

ScHizASTEK  ARMiGER  Clark,  u.  sp.  (p.  152). 

U.  S.  Nat.  Mus.  141104,  type. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 

SCHIZASTER   sp.    (p.    152). 
Johns  Hopkins  Univ.  T  2001. 
Figure  2.  Fragment  of  the  test  showing  portion  of  ambulacrum  witli  adjacent  interambulacrum. 

LlNTHIA    WILMINGTONENSIS    Clark,  11.  S]).    (p.    152). 

U.  S.  Nat.  Mus.  166482,  type. 
Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.   Lateral  surface  of  the  test. 

299 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  LXXI 


/■ 


Ic 


-^m 


2c 


4li^^ 


3b 


EOCENE    ECHINOIDEA. 


Figure  la.  Upper  surface  of  the  test. 

lb.  Lower  surface  of  the  test. 

Ic.  Lateral  surface  of  the  test. 

Id.  Posterior  surface  of  the  test 


PLATE    LXXI. 

LiNTHiA  Ai.ABAMENsis  Clark,  Jl.  sp.  (p.  153). 

U.  S.  Nat.  Mus.  173371,  type. 


LiNTHIA    ALABAMENSIS   Clark,  11.  sp.   (p.  153). 

U.  S.  Nat.  Mus.  166483. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test, 
2d.  Posterior  surface  of  the  test. 


EUPATAGLTS    CAROLINENSIS    Clai'k,  11.  sp.   (p.  153). 

U.  S.  Nat.  Mus.  166484,  type. 
Figure  3a.  Upper  surface  of  the  test. 
3b .  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 

EiTpATAGUs  CAROLINENSIS  Clark,  n.  sp.  (p.  153). 

U.  S.  Nat.  Mus.  164674. 
Figure  4.  I-pper  siu-face  of  tlie  test. 

Macropneustes  CAROLINENSIS  Clark,  11.  sp.  (p.  154). 

U.  S.  Nat.  Mus.  164651,  type. 
Figure  5a.  Upper  surface  of  the  test. 
5b.  Lower  surface  of  the  test. 
5c.    Lateral  surface  of  the  test. 
5d.  Posterior  surface  of  the  test. 
300 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXII 


EOCENE    ECHINOIDEA. 


PLATE   LXXII. 

Macropneustes  moktoni  (Conrad)  (p.  155). 

U.  S.  Nat.  Mus.  146468. 
Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 

Sarsella  GREGORY!  Clark,  n.  sp.  (p.  155). 

Am.  Mus.  Nat,  Hist.,  type. 
Figure  2a.  Upper  surface  of  the  test. 
2b,  Lower  siu-face  of  the  test. 
2c,  Lateral  surface  of  the  test. 
2d.  Postei'ior  surface  of  the  test. 

39800°— 15 25  301 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXIII 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXIII. 

CiDARis  MORTONi  Couratl  (]1.  157). 

Boston  Soc.  Nat.  Hist.  1.555. 
FlouRK  1.  Portion  of  test. 

CiDARis  SMiTHi  Clark,  ii.  sp.  (p.  157). 

Alabama  Geo!.  Sui-vey,  type. 
FiGtjRE  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 

CiDARis  SMITHI  Clark,  n.  sp.  (p.  157). 

Alabama  Gaol.  Siu-vey. 

CiDARIS   GEOKGIANA   Clark,  11.  sp.  (p.  158). 
U.  S.  Nat.  Mus.  166485,  type. 

CiDAEIS    BRANNERI    Amolcl  (p.  158). 
Leland  Stanford  Junior  Univ.  1056,  type. 

CCELOPLEURUS    ALDEICHI    Clark,  11.  SJ).  (p.  158) 

U.  S.  Nat.  Mus.  (Aldrich),  type. 
Figure  6a.  Upper  surface  of  the  test. 
6b.  Lateral  surface  of  the  test. 


Figure  3.  Spine. 


Figure  4.  Portion  of  the  test. 


Figure  5.  Spine. 


CcELOPLEURUS    ALDRICHI    Cliuk,  11.  sp.   (p.  158). 
U.  S.  Nat.  Mus.  (  Aldrich). 


Figure  7a.  Upper  surface  of  the  test. 
7b.  Lower  surface  of  the  test. 
7c.   Lateral  surface  of  the  test. 


GaGARIA   AMERICANA   Claik,  11.  sp.  (p.  159). 

U.  S.  Nat.  Mus.  (Aldricli),  type. 


Figure  8a.  Upper  surface  of  the  test. 
8b.  Lateral  surface  of  the  teat. 

ao2 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  LXXIV 


Ic 


C) 


Id 


'^^iiiUiAc 


.,11 ..itakfi'mHiA 


2b 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXIV. 

ECHINOCYAMUS   VAUGHANI   Twdtcliell,  11.  sp.   (p.  160). 

U.  S.  Nat.  Mu8.  166486,  type. 


Figure  la.  Upper  surface  of  the  test,  X  2. 
lb.  Lower  surface  of  the  test,  X  2. 
Ic.  Lateral  surface  of  the  test,  X  2. 
Id.  Posterior  surface  of  the  test,  X  2. 


IjAganum  eldkidgki  Twitchell,  n.  sp.  (p.  160). 

U.  S.  Nat.  Mus.  164683,  type. 


Figure  2a.  Upper  surface  of  the  test. 
2b .  Lower  surface  of  the  test. 
2c.  Jyateral  surface  of  the  test. 
2d.  Posterior  of  the  test. 


303 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  LXXV 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXV. 

Laganum  archerensis  Twitchell,  ii.  sp.  {p.  161). 
U.  S.  Nat.  Mu3.  164667a,  type. 


Figure  la.  Upper  .surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 


Laganum  .iohnsoni  Twitchell,  n.  sp.  (p.  162). 
U.  S.  Nat.  Mus.  137202,  type. 


Figure  2a.  Upper  surface  of  the  test. 

2b.  Lower  surface  of  the  test. 

2c.  Lateral  surface  of  the  test. 

2d.  Posterior  surface  of  the  test. 


Laganum  floridanum  Twitchell,  ii.  sp.  (p.  163) 

U.  S.  Nat.  Mus.  137884,  type. 


Figure  3a.  Upper  surface  of  the  test. 

3b .  Lower  surface  of  the  test. 

3c.  Lateral  surface  of  the  test. 

3d.  Posterior  surface  of  the  test. 


Laganum  dalli  Twitchell,  n.  sp.  (p.  164). 

U.  S.  Nat.  Mus.  164667b,  type. 


Figure  4a.  Upper  surface  of  the  test. 
4b.  Lower  surface  of  the  test. 
4c.  Lateral  surface  of  the  test. 
4d.  Posterior  surface  of  the  test. 
304 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXVI 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXVI. 

Amblyptgus  merkilli  Twitchell,  n.  sp.  (p.  165). 

U.  S.  Nat.  Mus.  164934,  specimen  A,  type. 

Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Part  of  one  ambulacrum,  X  3 
Id.  Apical  system,  X  3. 

305 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXVll 


la 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXVII. 

Amblypygus  meeeiixi  Twitcholl,  ii.  sp.  (]>.  165). 
U.  S.  Nat.  Mus.  164934,  specimen  A. 


Figure  In,.  Lateral  surface  of  the  test, 
lb.  Posterior  surface  of  the  test. 


Amblypygus  merrilli  Twitchell,  n.  sp.  (p.  165). 
U.  S.  Nat.  Mus.  137870,  .specimen  B. 


Figure  2a.  Upper  surface  of  the  test 
2b.  Lower  surface  of  the  test. 
306 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LXXVIII 


A^^ 


^'mT-*    "f^^ 


la 


5c 


lb 


4a 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXVIII. 

Amblypygus  mereilli  Twitchell,  n.  sp.  (p.  165). 

U.  S.  Nat.  Mus.  137870,  specimen  B. 


Figure  la.  Lateral  surface  uf  the  test, 
lb.  Posterior  surface  of  tlie  test. 


Oligopygus  wetherbyi  De  Ijoriol  (p.  166). 
U.  S.  Nat.  Mus.  137SSla,  specimen  A. 


Figure  2a.  Upper  surface  of  tlie  test. 
2b.  Lower  surface  of  tlie  test. 
2c.   Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 


Oligopygus  wetherbyi  De  Loiiul  (p.  166). 
U.  S.  Nat.  Mus.  137881b,  specimen  B. 


Figure  3a.   Part  of  one  ambulacrum,  X  8. 
3b.  Apical  system,  X  5. 


Oligopygus  haldermani  (Conrad)  (p.  167). 

U.  S.  Nat.  Mus.  112506,  specimen  A. 
Figure  4a.  Upper  surface  of  the  test. 
4b.  Lower  surface  of  the  test. 
4c.   Lateral  surface  of  the  test. 
4d.  Posterior  surface  of  the  test. 

Oligopygus  haldermani  (Coiiratl)  (p.  167). 

v.  S.  Nat.  Mus.  164661,  specimen  B. 

Figure  5a.  Upper  surface  of  the  test. 
5b.  Lower  surface  of  the  test. 
5c.  Lateral  surface  of  the  test. 
5d.  Posterior  surface  of  the  test. 

307 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  LXXIX 


le 


2d 


2c 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXIX. 

Oligopygus  floridanus  Tmtchell,  n.  sp.  (p.  169). 

IT.  S.  Nat.  Mus.  1C4660,  type. 


Figure  la.  Upper  surface  of  the  test, 

lb.  Lower  surface  of  the  test. 

Ic.  Lateral  surface  of  the  test. 

Id.  Posterior  surface  of  the  test. 

le.  Apical  system,  X  4J. 

If.  Part  of  one  ambulacrum,  X  10. 


Cassidulus  (Pygorhynchus)   georgiensis  Twitchell,  n.  sp.  (p.  170). 
U.  S.  Nat.  Mus.  164347,  type. 


Figure  2a.   Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c,   Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 


Cassidulus   (Pygorhy'nchu's)  gouldii  (Bouve)  (p.  171). 
Boston  Soc.  Nat,  Hist.  1756,  specimen  A,  type. 


Figure  3a.   Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.   Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 
308 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXX 


^■J^i.'V.A?, 


3c 


'ith:\  ■■■■    .'</ 


■^>Si:i'l' 


.y 


■-*( 


•  ^^^  r'^^^J 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXX. 

Cassidulxts  (Pygorhynchus)  gouldii  (Boiive)  (p.  171). 
U.  S.  Nat.  Mus.  137904,  specimen  B. 


FiGURK  la.   Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.   Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test, 
le    Part  of  floscelle,  X  5. 
If.    Part  of  one  ambulacrum.  X  5i. 


Cassidulus  (Pygorhynchus)  gouldii  (Bouve)  (p.  171). 
U.  S.  Nat.  Mus.  137904a,  specimen  C. 


Figure  2a.   Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.   Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 

Cassidulus  (Pygorhynchus;  alabamensis  Twitchell,  n.  sp.  (p.  172). 

Johns  Hopkins  Univ.,  type. 
Figure  3a.   ITpper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.    Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 

39800°— 15 26  309 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXXI 


la 


lb 


3a 


3c 


Ic 


Id 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXXI. 

ECHINOLAMPAS    ALDRICHI  Twitcliell,  11.  Sp.   (p.    173). 

Johns  Hopkins  Univ.  T  1099,  specimen  A,  type. 

Figure  la.  Upper  surface  of  the  test, 

lb.  Lower  surface  of  the  test. 

Ic.  Lateral  surface  of  the  test. 

Id.  Posterior  surface  of  the  test. 

EcHiNOLAMPAS  ALDRICHI  Twitchell,  u.  sp.  (p.  173). 

Johns  Hopkins  Univ.  T  1099. 
Figure  2.  Part  of  floscelle,  X  4i. 

Agassizia  conradi  (Bouve)  (p.  174). 

U.  S.  Nat.  Mus.  164744. 
Figure  3a.   Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 
310 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXXII 


>         L        ■     ■     ^iiv' -■■■.•-?(   1,,'..' 


I,  •  ,  ''SjJ*-  '■,*    .^rW ''W 


-=*i 


2a 


2b 


3c 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXXII. 

ScHizASTER  FLORiDANUS  Clark,  11.  sp.  (p.  175). 

U.  S.  Nat.  Mus.  164655,  type. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 

EUPATAGUS  FLORIDANUS  Clark,  11.  sp.  (p.  176). 

U.  S.  Nat.  Mus.  137881,  type. 

Figure  2a.  Upper  surface  of  the  test. 

2b.  Lower  surface  of  the  test. 

2c.  Lateral  surface  of  the  test. 

2d.  Posterior  surface  of  the  test. 

ScHiZASTER  AMERICANA  Clark,  11.  sp.  (p.  176). 

U.  S.  Nat.  Mus.  165695,  type. 

Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Anterior  surface  of  the  test. 

311 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXXIII 


V 


la 


OLIGOCENE    ECHINOIDEA. 


PLATE   LXXXIII. 

ExrPATAGUs  FLORiDANUS  Clark,  n.  sp.  (p.  176). 
Wagner  Free  Inst.  Sci.,  specimen  B. 


Figure  la.  Upper  surface  of  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 


EuPATAGUs  FLORIDANUS  Clark,  n.  sp.  (p.  176). 
Mus.  Oomp.  Zool.,  specimen  0. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 
312 


U.  S.  QEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXXIV 


W^^^'^. 


6b 


f:- 


MIOCENE    STELLEROIDEA    AND    ECHINOIDEA. 


PLATE   LXXXIV. 

Ophioderma  (?)  sp.  (p.  178). 

Johns  Hcjpkins  I'niv.  T  1000. 
Figure  1.  Fragment  of  arms. 

Amphiura  sanct^cruci.s  Arnold  (p.  178). 

Stanford  Univ.  1078,  type. 
Figure  2.  Cast  of  dorsal  surface,  X  3. 

Amphiura  sanct.^crucis  Arnold  (p.  178). 

U.  S.  Nat.  Mus.  165431,  type. 
Figures.  Cast  of  ventral  surface. 

CcELOPLEtTRus  iMPROCERUS  (Conrad)  (p.  180). 

U.  S.  Nat.  Mus.  166487. 
Figure  4a.  Upper  surface  of  the  test. 
4b.  Lower  surface  of  the  test. 
4c.  Lateral  surface  of  the  test. 

CcELOPLEURUs  SLOANi  Clark,  n.  sp.  (p.  181). 

r.  S.  Nat.  Mus.  166488,  type. 
Figure  .5a.  Upper  surface  of  the  test. 
5b.  Lateral  surface  of  the  test. 

PsAMMECHiNUs  PHiLANTHROPUs  (Conrad)  (p.  181). 

Johns  Hopkins  Univ.  T  1001. 
Figure  6a.  Upper  surface  of  the  test. 
6b.  Lower  surface  of  the  test. 
6c.  Lateral  surface  of  the  test. 


313 


U.    S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   LXXXV 


MIOCENE    ECHINOIDEA. 


PLATE   LXXXV. 

SiSMONDIA   (?)  ARNOLDI  TwitchcU,  11.  sp.   (p.    182). 

U.  S.  Nat.  Mus.  165.538,  type. 


Figure  la.  Upper  surface  of  the  test,  X  2. 
lb.  Lower  surface  of  the  test,  X  2. 


SiSMONDIA   (?)   COALINGAENSIS  Twitcliell,  11.  sp.   (p.    183). 

U.  S.  Nat.  Mus.  165717,  tyjje. 


Figure  2a.  Upper  surface  of  the  test,  X  2. 
2b.  Lower  surface  of  tlie  test,  X  2. 
2c.  Lateral  surface  of  the  test,  X  2. 


SCUTELLA    ANDERSONI  Twitchell,  11.  sp.    (p.   183). 

U.  S.  Nat.  :N[us.  165719,  type. 
Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  siu'face  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 

SCUTELLA    FAIRBANKSl    Pack    (p.   184). 

Univ.  California,  specimen  A,  type. 
Figure  4.  Upper  surface  of  the  test. 

SCUT'ELLA    FAIRBANKSl    Pack    (p.   184). 

U.  S.  Nat.  Mus.  164963.  specimen  B. 

Figure  5.     LTpper  surface  of  the  test. 

ScUTELLA    FAIRBANKSl    Pack   (]).   184). 

U.  S.  Nat.  Mus.  164963,  specimen  C. 

Figure  6.     Upper  surfat'e  of  the  test,  X  1^- 

ScUTELLA    (?)    MERRIAMI    (Audei-BOll)    (p.   185). 

U.  S.  Nat.  Mus.  165716,  specimen  A. 

Figure  7a.  Upper  surface  of  the  test,  X  2. 
7b.  Lower  surface  of  the  test,  X  2. 
7c.  Lateral  surface  of  the  test. 

ScuTELLA   (?)  MERRIAMI  (Aiidersoii)  (p.  185). 

U.  S.  Nat.  Mus.  165584,  specimen  B. 

Figure  8a.  Upper  surface  of  the  test,  X  2. 
8b.  Lower  surface  of  the  test,  X  2. 


ScuTELLA  NORRisi  Pack  (p.  186). 
Uriiv.  California,  type. 


Figure  9.     Lower  surface  of  the  test. 
314 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LXXXVI 


/ 


MIOCENE     ECHINOIDEA. 


PLATE   LXXXVI. 

ScuTELLA  ABERTi  Courad   (p.  187). 

Maryland  Geol.  Survey. 
Figure  la.  Upper  surface  of  the  test. 

lb.  Enlarged  plate  of  the  same  species. 

313 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LXXXVII 


v-"^ 
V^    ^ 


V 
-^^ 


"X 


Id 


X 


'.  -    ^  I. 


"^.^^ 


/ 


^^^teiissiiiii^M; 


--'^"^^S^"' 


_^^^te<r■.W'>i^i-;'•■'C"^^■^'^^■:.^,;^^i^^^^^^'■iii^»ife^^*^^^^ 


lb 


MIOCENE     ECHINOIDEA. 


PLATE   LXXXVII. 

ScuTELLA  ABERTi  Coiirad  (p.  187). 


Maryland  Geol.  Survey. 


Figure  la.  Lower  surface  of  the  test, 
lb.  Lateral  surface  of  the  test. 
Ic.  Interambulacral  plate. 
1(1.  Another  view  of  same. 
316 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  LXXXVIM 


3a 


lb 


4a 


4b 


4c 


MIOCENE    ECHINOIDEA. 


PLATE   LXXXVIII. 

ScuTELLA  GABBi  (Remond)  Merriam  (p.  189). 

Univ.  CaUfornia  19425. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lateral  surface  of  the  test. 

Dendeaster  perrini  (Weaver)  (p.  190). 

U.  S.  Nat.  Mus.  1G5.560,  specimen  A. 
Figure  2.     Upper  surface  of  the  test. 

Dendeaster  perrini  (Weaver)  (p.  190). 

U.  S.  Nat.  Mus.  165560,  specimen  B. 

FiGUSE  3a.  Upper  siu'face  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 

Dendraster  arnoldi  Twitchell,  n.  sp.  (p.  192). 

U.  S.  Nat.  Mus.  165707,  type. 
Figure  4a.  Upper  surface  of  the  test. 
4b.  Lower  surface  of  the  test. 
4c.  Lateral  surface  of  the  test. 
4d.  Posterior  surface  of  the  test. 

39800°— 15 27  317 


U.   S.  QEOLOQICAL  SURVEY 


MONOGRAPH    LIV      PLATE   LXXXIX 


// 


^°^.M<i 


--"^^'■^^'^^-litft 


X 


MIOCENE    ECHINOIDEA. 


PLATE   LXXXIX. 

Dendraster  gibbsii  (Remond)  (p.  193). 

V.  S.  Nat.  Mus.  165547,  specimen  A. 
Figure  la.  Upper  surface  of  the  test, 
lb.  Lateral  surface  of  the  test. 

Dendraster  gibbsii  (Remond)  (p.  193). 

U.  S.  Nat.  Mus.  165611,  specimen  B. 
Figure  2.  Lower  surface  of  the  test. 

Dendraster  gibbsii  (Remond)  (p.  193). 

U.  S.  Nat.  Mus.  165611,  specimen  0. 
Figure  3.  Upper  surface  of  the  test. 

Dendraster  gibbsii  (Remond)  (p.  193). 

U.  S.  Nat.  Mus.  165704,  specimen  D. 
Figure  4.  Upper  surface  of  the  test. 
318 


U.   S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XC 


-^^.■^.JI:Vv/';,-•7/,A;,.,,.^,7i    -.      -  /,■  .-^•■.' 


j>fv-'-'-,ZY*>sC»? 


2a 


MIOCENE    ECHINOIDEA. 


PLATE   XC. 

Dendraster  oregonensis  (Clark)  (p.  195). 

U.  S.  Nat.  Mus.  153975. 
Figure  1.  Upper  surface  of  the  test. 

Dendraster  coalingaensis  Twitchell,  n.  sp.  (p.  196). 

U.  S  Nat.  Mus.  165537,  type. 
Figure  2a.  Upper  surface  of  the  test. 

2b .  Lower  surface  of  the  test,  X  2 . 
2c.  Lateral  surface  of  the  test,  X  2. 

319 


U.   S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   XCI 


MIOCENE    ECHINOIDEA. 


PLATE   XCI. 

Mellita  caroliniana  Ravenel  (p.  204). 

Acad.  Nat.  Sci.  Philadelphia  1083. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lateral  surface  of  the  test. 
320 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XCll 


"■'%,, 


^^rm 


\ 


*     r---^ 


\ 


:^a?50^?HS!(15CJ!? 


^tl^^r  i     mtt 


lb 


MIOCENE    ECHINOIDEA. 


PLATE   XCII. 

Mellita  caroliniana  Ravenel  (p.  204). 

Acad.  Nat.  Sci.  Philadelphia  1083. 

Figure  la.  Lower  surface  of  the  test. 

lb .  Posterior  surface  of  the  teat. 

321 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XCIII 


MIOCENE    ECHINOIDEA. 


PLATE  XCIII. 

ScuTASTER  ANDERsoNi  Pack  (p.  206). 

Univ.  California,  type. 
Figure  1.  Upper  surface  of  the  test. 

En  COPE  MACROPHOEA  Ravencl  (p.  206). 

Acad.  Nat.  Sci.  Philadelphia  1086,  specimen  A. 

Figure  2a.   Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.   Lateral  surface  of  the  test. 
2d.  Posterior  surface  of  the  test. 
2e.   Apical  system,  X  SJ. 
322 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XCIV 


MIOCENE    ECHINOIDEA. 


PLATE   XCIV. 

Encope  maceophora  Ravenel  (p.  206). 

U.  S.  Nat.  Mus.  164658,  specimen  B. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.   Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test, 
le.   Part  of  one  ambulacrum,  X  8. 
If.    Apical  system,  X  5. 

Encope  macrophora  Ravenel  (p.  206). 

U.  S.  Nat.  Mus.  9970,  specimen  C. 
Figure  2.  Upper  surface  of  the  test. 

AsTRODAPSis  ANTiSELLi  Conracl  (p.  198). 

U.  S.  Nat.  Mus.  165466,  specimen  A. 
Figure  3.  Upper  surface  of  the  test. 

AsTRODAPSis  ANTISELLI  Conrad  (p.  198). 

U.  S.  Nat.  Mus.  165466a,  specimen  B. 

Figure  4a.   Lower  surface  of  the  test. 
4b.  Lateral  surface  of  the  test. 


323 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XCV 


MIOCENE    ECHINOIDEA. 


PLATE   XCV. 

ASTRODAPSIS    ARNOLDI    Twitcliell,  11.  sp.   (p.   199) 

U.  S.  Nat.  Mus.  165594,  type. 
Figure  1.  Upper  surface  of  the  test. 

ASTKODAPSIS   WHITNEYI   Reiiioiid  (p.  201). 

Univ.  California  19426. 
Figure  2a.   Upper  surface  of  the  test. 
2b.  Lower  surface  of  tlie  test. 
2c.  Lateral  surface  of  the  test. 

AsTROD APSIS  TUMiDUS  R6mond  (p.  202). 

Univ.  California  19424. 
Figure  3a.   L'pper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 

AsTRODAPSis  jACALiTOSENSis  Arnold  (p.  203). 

U.  S.  Nat.  Mus.  165610,  type. 
Figure  4.  Upper  surface  of  the  test. 

Cassidulus  bassleri  Twitchell,  n.  sp.  (211). 

U.  S.  Nat.  Mus.  9476,  type. 
Figure  .5a.   Upper  surface  of  the  test. 
5b.  Lower  surface  of  the  test. 
5c.   Lateral  surface  of  the  test. 
5d.  Posterior  surface  of  the  test. 
324 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV      PLATE   XCVI 


MIOCENE    ECHINOIDEA. 


PLATE   XCVI. 

Clype ASTER  BOWERSi  Weaver  (p.  209). 
Univ.  California,  type. 


P''iGUHB  la.   Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 


Clypeaster  (?)  BREWERiANUs  (Remond)  (p.  210). 
Acad.  Nat.  Sci.  Philadelphia  1088,  specimen  A. 

Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.   Lateral  surface  of  the  test. 

Cltpeaster  (?)  BREWERIANUS  (R6mond)  (p.  210). 

Univ.  California  19423,  specimen  B. 
Figure  3.  Upper  surface  of  the  test. 

39800°— 15 28  325 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XCVII 


'^■^■wm^w^ 


le 


la 


lb 


2a 


2b 


2c 


Id 


MIOCENE     ECHINOIDEA. 


PLATE   XCVII. 

Agassizia  porifera  (Ravenel)  (p.  212). 
Am.  Mus.  Nat.  Hist. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Posterior  surface  of  the  test. 
Id.  Lateral  surface  of  the  test. 


Echinocardium  orthonotum  Conrad  (p.  213). 
Acad.  Nat.  Sci.  Philadelphia  1079. 


Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 
326 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE   XCVIll 


Ic 


MIOCENE    ECHINOIDEA. 


PLATE   XCVIII. 

ECHINOCARDIUM    ORTHONOTUM  Coill'ad  (p.  214). 

Am.  Mus.  Nat.  Hist. 
Figure  la.  Upper  surface  of  the  test, 
lb.  Lmver  surface  of  the  test. 
Ic.  Anterior  surface  of  the  test. 

ECHINOCARDIUM    ORTHONOTUM  Coiirad   (p.  214). 

Johns  Hopkins  Univ.  T  1002. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 
2c.  Lateral  surface  of  the  test. 

ECHINOCARDIUM   DEPRESSUM  Clark,  11.  sp.   (p.  214). 

U.  S.  Nat.  Mus.  164454,  type. 
Figure  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 

LiNTHiA  (?)  CALiFORNiCA  Weaver  (p.  214). 

Univ.  California,  type. 
Figure  4.  Upper  surface  of  the  test. 

327 


U.  S.  GEOLOQICAL  SURVEY 


MONOGRAPH   LIV     PLATE  XCIX 


la 


PLIOCENE    ECHINOIDEA. 


PLATE   XCIX. 

Strongylocentrotus  brobachiensis  (Miiller)  (p.  216). 

Wagner  Free  Inst.  Sci.  4350. 

Figure  la.  Upper  surface  cif  the  test, 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 

DiPLOTHECANTHUS    DALLI  Twitchell,  11.  sp.    (p.  218). 

U.  S.  Nat.  Mu.s.  164670. 
Figure  2a.  Posterior  surface  of  the  test. 
2b.  Lateral  surface  of  the  test. 
328 


U.  S.   GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  C 


lb 


PLIOCENE    ECHINOIDEA. 


PLATE   C. 

DlPLOTHECANTHUS    DALLI  Twitclioll,  H.  sp.    (p.  218). 

U.  S.  Nat.  Mils.  164070,  type. 
Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 

Dendraster  inteelineatus  (Stimpsoii)  (p.  216). 

Univ.  California  19427. 
Figure  2a.  Upper  surface  of  the  test. 
2b.  Lower  surface  of  the  test. 

329 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV     PLATE  CI 


PLIOCENE    ECHINOIDEA. 


PLATE   CI. 

ASTEOUAPSIS    FEKNANDOENSIS    Pack  (p.  217). 

Univ.  California,  specimen  A. 
Figure  1.  Upper  surface  of  the  test. 

ASTRODAPSIS    FERNANDOENSIS    Pafk  (p.  217). 

Univ.  California,  specimen  B. 
Figure  2.  Lower  surface  of  the  test. 

Cassidulus  berryi  Twitchell,  ii.  sp.  (p.  220). 

Johns  Hopkins  Univ.  T  1,  type. 
E'lQURE  3a.  Upper  surface  of  the  test. 
3b.  Lower  surface  of  the  test. 
3c.  Lateral  surface  of  the  test. 
3d.  Posterior  surface  of  the  test. 

330 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  Gil 


la 


lb 


PLIOCENE    ECHINOIDEA. 


PLATE   CII. 

DiPLOTHECANTHUs  ROSACEus  (Lamarck)  (p.  219). 

U.  S.  Nat.  Mils.  165693. 
Figure  la.  Upper  surface  of  the  test, 
lb.  Lateral  surface  of  the  test. 

331 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH    LIV     PLATE  GUI 


PLIOCENE    ECHINOIDEA. 


PLATE   cm. 

DiPLOTHECANTHUs  ROSACEus  (Lamarck)  (p.  219). 
U.  S.  Nat.  Mu.s.  165693. 


Figure  la.  Lower  surface  uf  the  teat. 

lb.  Posterior  surface  of  the  test. 


ScHiZASTER  (?)  STALDERI  Weaver  (p.  221). 
Univ.  California,  type. 


Figure  2.  Upper  surface  of  the  test. 
332 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  CIV 


vmr- 


,  ,ur . 


'<'^ 


la 


'  ~  '['fif'"  ■  -  -I 


■»rTr''*jg^ 


PLEISTOCENE    ECHINOIDEA. 


PLATE   CIV. 

Dendraster  excentricus  (Eschscholtz)  (p.  223). 

Wagner  Free  Inat.  Sci.  2473,  specimen  A. 

Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.  Posterior  surface  of  the  test. 

39800°— 15 29  333 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  CV 


/ 


fe 


\ 


PLEISTOCENE    ECHINOIDEA. 


PLATE   CV. 

Dendraster  excentricus  (Eschscholtz)  (p.  223). 
Jiilins  Hopkins  Univ.  T  2,  specimen  B. 


Figure  la.  Upper  surface  of  the  test. 
lb.  Lower  surface  of  the  test. 
Ic.  Lateral  surface  of  the  test. 
Id.'  Posterior  surface  of  the  test. 
334 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  CVI 


PLEISTOCENE    ECHINOIDEA. 


PLATE   CVI. 

Mellita  pentapora  (Gmelin)  (p.  225). 

Johns  Hopkins  Univ.  T  3. 
Upper  surface  of  the  test. 

335 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  CVII 


PLEISTOCENE    ECHINOIDEA. 


PLATE   CVII. 

Mellita  pentapora  (Gmelin)  (p.  225). 
Johns  Hopkins  Univ.  T  4,  type. 


FiGUKE  la.  Lower  surface  of  the  test. 

lb.  Posterior  surface  of  the  test. 
Ic.  Part  of  an  ambulacrum,  X  6. 
336 


i 


U.  S.  GEOLOGICAL  SURVEY 


MONOGRAPH   LIV     PLATE  CVIll 


-t.    ASTRODAPSIS    TUMIDUS     REMOND     IN     MATRIX,    SANTA    MARGARITA     FORMATION    (UPPER 
MIOCENE),    NACIMIENTO    RIVER,    SAN    LUIS    OBISPO    COUNTY,    CAL. 


■*«*.  _  .Jt'SL'T]^ 


S.    DENDRASTER    GIBBSII    (REMOND)    IN    UPPER    MIOCENE  (?)    BEDS,    K.    W.    JONES    RANCH,    KINGS 
COUNTY,   20    MILES    SOUTHEAST    OF    COALINGA,    FRESNO    COUNTY,    CAL. 


INDEX. 


Names  in  italic  are  synonyms;  figures  in  italic  refer  to  illustrations;  figures  in  black  face  refer  to  descriptions. 


A. 

Page. 

Atiert,  J.  J.,  species  named  after 187 

Acknowledgments  for  aid 7 

Agassizia  clevei 175 

comadi 174-175,  SW 

excentrica 175 

excentrica  A.  Agassiz 212 

floridana 174 

poritera 212-213,  S26 

Aldrich,  T.  H.,  species  named  after 173 

Amblj'pygus  altus 165-166 

americanus 165-166 

merrilli 165-166,  SOS,  SOB,  S07 

Amph idclus  ampliphoTus 214 

gothicus 214 

orthonotus 213 

virginianus 213 

Amphiura  sanct£ecrucis 178-179,  JJ  J 

AmphiuridsB 23. 178-179 

A  nanckytcs  ductus S3 

crucifcrus 71 

ftmbriaius 83 

ovalis 81-82,^64 

texana i2,S64,mS 


sp.. 


83 

A  napcsus  carol inus 222 

Anderson.  F.  M.,  cited 140,185-186 

species  named  after 183 

Antedonida? 112 

Arachnoides  placenta 190 

A  rhacia  sp.  Bouve 117 

sp.  Stefanini 180 

Arbaciidse 117, 158-159. 180-181 

Arbacina 31-32,62-53, 117, 158-159, 180-181 

Arnold,  Kalph,  acknowledgment  to 7 

cited 114, 158, 178-179, 223 

species  named  after 182,192,200 

Aspidura  idahoensLs 2i,B30 

Asteracanthion  lincki 222 

As^Jerias  dubium 28-29, ;?.?;,' 

lincki 222 

rcmondi 178 

remondii 178 

stellionura 222 

vulgaris 222 


sp. 


112 

Asteriida; : 28-29. 112, 178, 222 

Astemata 34, 67-81, 140-150, 165-174,  211-212,  220-221 

Asteroidea 28-23, 41-43, 112, 178, 222 

Astrodapsis 197 

antiselli 187,198-199, 200, 203, 217, 218, 5.'3 

antisclli  var.  arTioldi  Pack 199 

amoldi 199-201, 202, 204,  S'H 

hnwcrianus 210 

femandoensis 217 

jacalitosensis 200, 202, 203-204,  S2i 

merriami 185 

pcrrini 190 

tumidus 199, 202, 202-203, 210, 324, 337 

whitneyi 187, 199, 200, 201-202, 203, 324 

whitncyi 199 

sp.  a  Arnold Itl2 

sp.  indct.  Arnold 182 

Astropecteii  montanus 41, 2SS 

Astropectinidffi 41 

Atelostomata 34, 67-100, 140-166, 165-177, 211-215, 220-221, 227 

AtheneidEE 42 

39800°— 15 30 


Page. 

Berry,  E.  W.,  species  named  after 220 

Bibliography  of  Cenozoic  echinoderms 105-111 

of  Mesozoic  echinoderms 14-20 

Botriopygus  alabamensis 68-69, 253 

elevatus 69 

Bourgueticrinidge 39-40 

BouTgueticrinus  sequalis 40 

alabamensis 39 

ellipticus 40 

Breynella  equizoata 148 

gregoryi 148, 297 

Brissopsis  californica 214 

poriferus 212 

rimulatus 154 

Brissus  spatiosus 215 

C. 

Calycina 49-51 

Cardiaster  cinctus 83-84, 84, 263 

curtus 84-85, 2eff 

fimbriatvs 83 

smocki 84,  SS5 

Cassidulidaj 34, 72-81, 140-150, 170-174, 211-212. 220-221 

Cassidulus  abruptus 81 

scquoTeum 75 

ffiquoreus 75, 75-76,  76, 80. 211, 212, 259 

amygdala 147 

bassleri 211-212. '221,324 

berryi 212, 220-221, 330 

californicus 140. 294 

conoideus 80-81, 256 

florealis 74-75, 76. 259 

hemisphericus 80,  ses 

intermedius 79-80, 263 

micrococcus 76,  SO.  212, 260 

porrectus li,  261, 262 

stantoni 79, 282 

subangulatus 81 

subconicus 75, 77, 77-78, 261 

subquadratus 77, 78, 81,  ^^ 

(Pygorhynchus)  alabamensis 172,172-173,309 

carolinensis 116, 146-147, 171, 296 

conradi 145-146, 147,  296 

georgiensis 147, 170-171, 30S 

gouldii 171-172, 173, 30«,  309 

(Rhj-nchopygus)  depressus 143, 144, 144-145, 295 

holmesi 140-141, 294 

lyelli 141-142, 294 

patelliformis 143-144, 145, 295 

raveneli 142-143, 115, 294,295 

Catopygus  columbarius 73 

conradi 145 

oviformis 72-73, 73, 74, 268 

patelliformis 143 

pusillus 73, 74, 258 

wiUiamsi 73-74,  «5S 

sp.  indet 74 

Cenozoic  echinoderms,  geologic  distribution  of 101, 102-104 

Cenozoic  formations,  American,  stratigraphic  position  of 102 

Chiridota  sp 177 

Cidaridaj 23-24. 30-31. 44-49, 113-116, 167-158, 179 

'  Cidaris  alabamensis 116 

Cidaris  armiger 46 

armigera , 46 

blandis 116 

brarmeri 45, 158. 302 

californicus 30. M.S33 

337 


338 


INDEX. 


Page. 

Cidaris  carolinensis IIS-IU,  114,  «S4 

davigaa ^ 

diatretum 49,56 

diUeri 23-24.230 

dixiensis 47, 2SS 


georgiana . 


Ki.SOi 


hemigranosus 48 

merriami 114-115, 158, 2S4 

mitchelli 113,114,584 

modestus ^1* 

moereus ^^^ 

mortoni 157,  SOi 

nahalakensis *8 

ordinatus 11^ 

perdubius 11® 

plumasensis 31,  *SS 

pratti n^,2S^ 

sceptrifera 45, 56 

serrata 47 

serrifer 47 

shastensis 23, 24, 230 

smithi 157,302 

splendens 46, 46-47, 2SS 

taylorensis 3()-31, 233 

tehamaensis 44, 258 

texanus 45, 238 

thouarsii l''^ 

walcotti *5-46, 238 

sp 46 

sp.  De  Cregorio 116 

Cidarites  armifjer 46 

diatretum 56 

splendeus 46 

Cidaroidea 23-24, 30-31, 44-49, 113-116, 157-158, 179 

Clark,  H.L.,  cited 115,179 

Clypeaster  ambigenus ; 138 

biarritzensis 13S 

bowersi 209, 32o 

breuniger 209 

brewerianus 210, 3£5 

ooncavus 138 

cotteaui 138 

crassicostatus 219 

douvillei 137,138 

fioTealis 74 

gabbi 189,211 

ffeometrkus 72 

jomsi 137 

j(m€sii 136, 137 

rogersi 128,136-138,293 

rosacetta 219 

simplex 138 

tumidus 136,137 

turgidus 137 

sp 72,74 

Clypeastridffi 67,136-139,209-211,218-220 

Clj-peastrina 67, 119-139, 160-164, 182-211, 216-220, 223-227 

Coelopleurus  aldrichi 158-159,, JfJ2 

depressus 117 

improcerus 180, 181, 313 

intulatus 117, 285 

sloani 181, 213 

( Echinus)  injiatus 117 

Collections  studied 7 

Coptosoma  mortoni 62, 62-63,  ISl 

speciosum 61-62, 63, 2^8 

Cottaldia  rotula 57, 2^9 

Couper,  J.  Hamilton,  cited  by  Conrad 145 

Craigin,  F.  W.,  cited 34, 47, 57, 82 

Cretaceous  echinoderms,  descriptions  of 35-100 

stratigrapbic  distribution  of,  in  Texas 14 

types  represented  among 9-10,12-13 

Crinoidea 21-22,25-28,35-40,112 

Crj-ptozonia 2S-29, 112, 178, 222 

Cyphosoma  hilli 59-60,  S48 

mortoni 62 

speciosum 61 

texana 60 


Page. 

Cyphosoma  texanum 58,60,60-61,61,250 

volanum 60, 61, 250 

Cyphosomatidoe 63-63, 118, 159 

T>. 

Ball,  W.  H.,  acknowledgment  to...! 7 

species  named  after 164 

De  Loriol,  P . ,  cited 39 

Dendraster 190 

amoldi 191, 192-193, 197, 317 

ashleyi 193 

coalingaensis 193, 194, 196-197, 225,3/9 

e.xcentricus 194, 196, 217, 223-225, 333,  S3i 

fairbanksi 217 

gabbi 217 

gibbsii 193-195, 196, 224, 225,  S18 

interlineatus 185, 195, 197, 216-217, 3S9 

oregonensisj 185, 195, 217, SiS 

perrini 129, 190-191, 192, 193, 317 

sp 197 

Dendrocrinoidea 21-22, 25-28, 35-39 

Desor,  E .,  cited 67 

Diadema  texana 60 

texanum 55, 60 

DiadematidK 32, 65-58 

Diademlna 32-33, 54-63, 118, 159 

Diademoidea 31-33, 49-65, 117-118, 168-159, 180-182. 216. 222-223 

Dicyclica 21-22, 25-28, 35-40, 112 

Diplopodia  hilli 59 

streeruvitzi 58, 68-59,245 

tafB 58.249 

texa  na 60 

texanum 60 

Diplopodiida- 58-59 

Diplothecanthus  dalli 218-219, 220,  .328,  SS9 

rosaceus 209, 219-220,  S31,SSS 

Discoidea  haldermani 167 

Ditremastcr  conradi 174 

Dumhlca  symmetrica 64 


Echinanthus  antillarum 148 

bonissenti 148 

georgiensis 139, 29^ 

mortonis 67 

quinquefaria 128 

rogersi 136 

rosaceus 219 

rosaceus 219 

subcarinatus 139 

Echinarachnius 124, 190 

ashleyi 193 

breicerianus 210 

excentricus 190, 193, 223 

fairbanksi 184 

gabbi 189 

gibbsii 193, 196 

juliensis 125 

norrisi 186 

parma 190 

sp.  Conrad 197 

Echinina 63-65, 118, 159,181-182, 216, 222-223 

Echinobrissus  angustatus 69, 256 

crucifer 71 

e.xpansus 69-70, 70,«W 

t  e.xanus 70, 257 

Echinocnrdium  amplitlorus 214 

ampliphorus 214 

cordatum 214 

depressum 214, 327 

gotbicus 214 

orthonotum 213-211, 214,32/, S«« 

ortkonotus 213 

pennatifidum 213 

virginiinum 213 

Echino-cidaris  infulatus 117 

Echinocidaris  sp.  McCrady 180 

Ecbinocorytliidie 81-86 


INDEX. 


339 


Page. 

Echinocyamus  huxleyanus 119, 119-120, 120, 122, 160,  me 

mcridionalis 121 

parvus 119. 120.  lUO 

texanus 119, 120. 160. 2Se 

vaughani 119, 120, 160,  SOS 

Echinodiscus  perrini 190 

Echinoidea. .  23-24, 30-34, 44-100, 113-156. 157-177, 179-215, 816-221, 222-227 

Echinolampas  affinis 1"! 

aldrichi 1.50, 173-174, 310 

appcndiculatus 149-150,  m,g97 

francei 150 

insi.t^iis 1"4 

Echinoneida? 67-68 

Echinus  andinus 53 

exerceus 118 

improcerus 180 

infulatus 117 

patagonensis 5.3 

pentoporus , 225 

philantfiTopus 181 

placenta 124, 190 

reticulatus 219 

Tuffini 181 

varkgaius 222 

sp 118,  SSS 

sp.  Aldrich 118 

sp.  Cunningham 159 

sp.  Morton 46 

Eldridge,  G.  H.,  species  named  alter 161 

Emmons,  Ebenezer,  cited 119 

EnallastiT  inflatus 86 

mexicanus 88 

obliquatus 87-88, 269 

peruvianus 87 

texanus 86-87, 87, 268 

sp 86 

Encope  cite 208 

emarginata '. 208 

grandis 208 

macrophora 206-203,  SSS,  SSS 

tenuis 208 

Encrinidce 22 

Encrinus  hj-atti 22, 230 

Eocene  echinoderms,  descriptions  of..' 112-156 

eastern  Gulf,  stratigraphic  distribution  of 104-105 

Epiastcr  eUclus 88 

elegans . ! 88 

hemiasterinus 89 

ivhitei 89 

Eupatagus  carolinensis 153-154, 300 

clevei 176 

floridanus 176-177, 311,312 

Eurhodia  morrisii 143 

F. 

Favjasia  florealis 74 

Fibularia  meridionalis 121-122, 2S6 

Fibulariid[e 1, 119-122, 160, 182-183 

Flexibilia 39-40,112 

G. 

Gabb,  W.  M.,  cited 178 

Gagaria  americana 159,302 

G  alerites  oregonensis 212 

Geologic  distribution  of  Cenozoic  echinoderms 101. 102-104 

Gnathaster  elongatus 42 

Gnathostomata 33-34, 65-67, 119-139, 160-164, 182-211, 216-220,  223-227 

Goniaster  mammillata 42,  S37 

Gonioclypeus  subangulatus 81 

Goniopygus  major 53 

zitteli 53-53,  SiS,  2U 

Gregory,  J.  W.,  acknowledgment  to 7 

species  named  after 148 

H. 

Hadouinia  mortoni 67 

BcmiasteT  americanus 94, 95 

beecheri 96-97, 279 

bexari 89-90,275 


Page. 

Hemiaster  californicus 96, 279 

calvini 90, 91, 276 

comanchei 90, 275 

conradi 174 

dalli 90, 90-91, 97, 276 

elegans 88-89, 89, 90, 270, 271, S7S 

humphreysanus 95-96, 96, 27S 

incrassatns ; 93 

kiimmeli 97-98,  gg,  ggt 

lacunosus 97, 37$ 

parastatus 92, 93, 97, 98, 277 

Stella 93, 97, 277 

texanus 94-95,  S78 

ungula 92, 93-94, 277 

wclleri 98, 2S/ 

wetherbyi 93 

whitei 88, 89, 90, 01, 272, 27S,  274 

(^Perkosmos)  spatiosiLS 215 

Hemicidaridne 31-32, 52-53 

Hemicidaris  intumescens 31-32, 233 

Hemipatagus  argutus 150, 151 ,  298 

subrostratus 150, 151, 298 

Hemipedina  charltoni 57-58 

Heterodiadema  ornatum 56-57,  S47 

Hill,  Robert  T.,  acknowledgment  to 7 

Holaster  cinclus 83 

comanchesi 85 

computus 85 

fimbriatu-s 83 

Isevis  var.  planus §5 

mortoni 155 

nanus 85 

parastatus 92 

simplex 85-86, 2fiS,  267,  S68 

supernus 85 

ungula 94 

Holectypina 33-34, 65-66 

Hokctypus  charltoni 66 

craigini 34, 2.3.4 

pealei 33-34, 234 

planatus 34, 65-66, 2S4,  SSS 

planus 65 

transpccoscnsis 66 


sp.. 


66 

Holmes,  F.  S.,  species  named  after 140 

Holothurioidea 177 

H j-podiadema  elegans 52, 2.f3 

I. 

Inadunata 21-22, 25-20. 35-39 

Irregularia 33-34, 65-100, 119-156, 160-177, 182-215, 216-221 ,  223-227 

Isocrinus  asteria 26 

californicus 21-22,230 

decorus 26 

knighti 25-26, 27, 231,  SSS 

naresianus ", . .       26 

parrfe 26 

smithi 21,230 

wyvillc-thomsoni 26 

sp 22 

,    J. 

Jurassic  echinoderms,  descriptions  nf 25-34 

scarcity  of 9 

tj^pes  represented  among 12-13 

L. 

Lagana  rogcrsi 136 

Laganidse 122-123, 160-164 

Laganum  archerensis 123, 161-162, 163, 164, 304 

crustuloides 122-123, 162, 163, 164, 2S6 

dalli 123, 162, 164, 304 

eldridgei 160-161, 30S 

elongatum 161 

floridanum 123, 162, 163-164, 304 

johnsoni 123, 162-163, 304 

reflexum 123 

Leiocidaris  hemigranosa 48 

hemigranosus 45,48-49,235 


340 


INDEX. 


Page. 

Leptarbacia 53 

argutus 53, 2^5 

Linthia  alabamensis 153, 300 

califomica 214-215. 327 

tumidula 93, 100, 282 

variabilis 99-100, 2S3 

wilmingtonensis 152-153,  ,\'?i* 

M. 

Macraster  texanus SS 

Macrophora  macrophora 206 

ravendU 206, 207 

Macropneustes  carolinensis 154, 300 

mortoni 155,. Wi 

Marsupites  americanus Z%,233 

test  LI  dinar  ius 39 

Maxsupitidii? 39 

McUUa  ampla 225, 226 

caroliniana 203-205, 220,520,351 

caroliniata 204 

pentapora 205, 225-227, 335, 336 

quinqucfora 225 

sexforis 205 

tcstudinata 225 

tcxana 225, 226 

Meoma  spatiosa 215 

vcntricosa 215 

Merriam,  John  C,  acknowledgment  to 7 

cited 189, 216-217 

Merriamastcr  pcrrini 190 

Merrill,  G.  P.,  species  named  after 165 

Mesozoic  echinoderms,  geologic  distribution  of 12-13 

Mesozoic  formations,  American,  stratigraphic  positions  of 11 

Metalia  holmesi 215 

raveneliana 215 

Micrastcr  unguja 93 

Microcrinus  conoideus 112 

Micropsis  lineatus , 63, 254 

Miller,  S.  A.,  cited 39 

Miocene  echinoderms,  descriptions  of 178-215 

Mcera  lachcsis 227 

Monostychia  marg'nmlis 127 

plana 121 

Mortonella 128 

quinquefaria  128. 130, 137, 1^1,289,290 

rogersi 128 

Mortonia  Desor 128 

jonesii 136 

quinqucfana 128 

Togersi 128, 136 

tumida 133, 137 

turgida 136, 137 

{Pcriarchus}  carolinensis 204 

lyelli 131 

margiTialis 126 

pilcus  sinensis 135 

plana 121 


K. 


71 

71 

141-142 

.       171 


NudcoUhs  crucifcr 

cruciferus ' 

lyelli 

mortoni 

oviformis 72 

Nucleolitidae 68-72, 165, 170 

Nuculites  crucifcT 71 

cruciferus 71 

O. 

Oligocene  echinoderms,  descriptions  of 157-177 

eastern  Gulf,  stratigraphic  distribution  of 104, 105 

Oligopygus 166 

costulatus 167 

floridanus 167, 168, 169-170, 308 

haldermani 157, 167-169, 170,  S07 

o\'um-serpentis 167, 168, 170 

wetherbyi 166-167, 168, 170, 507 

Ophioderma  bridgerensis 43 

sp 178, SIS 


Page. 
OphiodermatidEe 178 

Ophioglypha  bridgerensis 43-44, 237 

texana 43, 44 ,  257 

utahensis 29,  ^55 

Ophiolepididse 29, 43-44 

Ophim-oidea 23, 29, 43-44, 178-179 

OpL^saster  conradi 174 

Orthechinus  pretiosus IIS,  285 

Orthopsidje 54-55 

Orthopsis  occidentalis 54-55,  £4^ 

planulata 54,  S4S 

P. 

Pack,  R.  W.,  cited ia7, 206, 217 

Paractinopoda .' 177 

Pedinidae 33 

Pedinopsis  pond  i ;.......: 65, 2SS 

symmetrica : 64, 25S 

Pentaceros  asperulus 42-43, 237 

Pentacerotidre : 42-43 

Pentacrinid^ 21-22, 25-28, 35-36 

Pentacrinitcs  asteriscus 25, 26, 27 

Pentacrinus  asteriscus 22, 25, 26, 26-27, 28, 232 

beaugrandi 26 

bryani 35-36, 235 

shastensis : 27, 28, 23£ 

tehamaensis 35, 36, 235 

whitei 26, 27, 27-28, 232 

(Cainocrinus )  andreas 26 

Pentagonaster  arculatus 41 

browni 41-42, 236 

Pentagonasteridae 41-42 

Periarchus 130 

altus 130-131, 188, 2S7 

carolinensis 204 

crustuloides 122 

lyelli 125, 126, 127, 130, 131, 131-133, 136, 18S,S90,291 

marginalis 127 

pileus-sinensis 133, 134, 135-136, 292 

plana 121 

protuberans 133, 133-134, 136, 291 

sp.  a  Stefanini 132 

sp.  b  Stefanini 130 

Periaster  australis 95 

Pericosmvs  spatiosus 215 

Phanerozoma 41-43 

Phymosoma  texanum 60 

Pinnata 39-40, 112 

PlagiobrisstLS  holmesi 215 

raienelianus 215 

Plagionotis  ravenelianus 215 

Plagionotus  holmesii 215 

ravenelianus 215 

Pleistocene  echinoderms ,  descriptions  of 222-227 

Pliocene  echinoderms,  descriptions  of 216-221 

Psammechinus  cingulatus 63-^4, 251 

exoletus 182 

i  mproceras 180 

philanthropus 181-182,  SIS 

ruffini 181 

Pseudodiadema  baileyi 32 

diatretum 5B,248 

emersoni Z2,2S4 

hilli 59 

ornatum 56 

roemeri 55 

speciosum 61 

tenue 55 

texanum 55, 57, 60, 61, 2^7 

Pygasteridgc 33-34, 65-66 

Pygorhyncus  crucifcr 71,142 

gouldii 171 

grignonensis 146, 171 

lyelli 141 

maveri 146, 147 

mortonis 67 

rugosus 147 

Pygurus  florealis 74 

geometricus 72 

sp 34 


INDEX. 


341 


Pyrina  bulloides 68 

dcsmoulinsii 68 

parryi 67-68,  ISS 

R. 

Ravenel,  Edmund,  species  named  after 142 

Eavenelia  cruci/eT 142 

gouhlii l"! 

RavenelUa  macTophoTa 20tl 

Resularia  ectobranchiata 31-33 , 

49-65, 117-118, 158-159, 180-182, 216, 222-223 

Rejularia  endobranchiata 23-24, 30-31, 44-49, 113-116, 157-158, 179 

Remond,  Auguste,  cited 211 

Rhizocrinus  alabamensis 39-40,  iO, SSS 

cylindricus 40,  «;35 

Rhyncbopygus  calderi 143 

pygmaeus 145 

■S. 

Salenia  bellula 51, 2^ 

desori 50 

petalifera . . . ". 50 

scutigera 50 

texana 49-50, 51, Sil,2i3 

tumidula 50-51, 51, 2i3 

Saleniida; 49-51 

Sarsella  gregoryi 155-156,  SOI 

Schizaster  americana 176, 311 

armiger 152, 209 

atropos 227 

floridanus 175, 31 2 

lecontei 151-152,  S98 

stalderi Z21,S3S 

sp 152, 299 

Scutaster 206 

andersoni 206,  S33 

Scutella 124 

aberti 187-189,  S/S,  SW 

albcTti 187 

andersoni 183-184,  Sli 

caput-Vmmsis 135 

caput-sinensis 135 

caTolinensis 204 

caroliniana ...' 204 

conradi 121, 123, 126, 126-127,fSJ 

crustuloides 122 

cicentrica 223 

fairbanksi 184-185, 186, 189,  SU 

faujasi 130 

gabbi 1S4, 185, 189, 211, 317 

gabbi  Merriam 211 

gibbsii 193 

interlincata 216 

jonesii 136 

lenticularis 190 

lydli 131 

macTophora 206 

meniami 183, 185-186, 314 

merriami '. 184 

mississippiensis 124-125, 126, 127, 133,  esS 

moTtoni 128 

norrisi 186-187, 3U 

parma 126, 190 

patagonensis 125, 194 

perrini 190 

pihus-sinensis 135 

quinque/aria 128 

quinquefora 225 

Todgcrsi 136 

Togersi 128, 129, 136 

striatnJa 125 

striatula 224 

subrotunda 188 

subtetragona 125 

tarraconensis 188 

tuomeyi 125-126, 127, 133,  SS9 


Page. 

Scutella  sp.  Conrad 197 

sp.  Emmons 130 

(EcMnarachnius)  excentricus 224 

orcgoncnsis 195 

( Mortonia )  rogcrsi 128 

Scutellaster  crotaceus 67 

Scutellida' 124-136, 183-209, 216-218, 223-227 

Sismondia  alia 130 

antillanim 164 

amoldi 182-183, 183,  SU 

coalingaensis 183,  S/4 

conradi 127 

crustuloides r 122 

lyelli 131 

marginalis 123, 126 

merriami 185 

pilcus-sinensls 135 

plana 121,  SSB 

Slocum,  Arthur  W.,  cited 79-80, 80, 97, 99-100 

Spatangidse 86-100, 150-156, 174-177, 212-215,  221, 227 

Spatangus  columbianum 87 

cor-marinum 92 

orthonotus 213 

pachecoensis 156 

parastatus 92 

Stella 93 

w  tigula 93 

sp 83,92,93 

Springer,  Frank,  acknowledgment  to 7 

cited 25,26,39,112 

Stanton,  T.  W.,  acknowledgment  to 7 

Stelleroidea 23, 28-29, 41-14. 112, 178-179, 222 

Stemata 81-100, 150-156, 174-177,  212-215.  221, 227 

Stomechinus  hyatti Zi,  2S4 

nudus 33 

Stratigraphic  distribution  of  eastern  Gulf  Eocene  and  Oligocene 

echinoderras 104-105 

Stratigraphic  positions  of  American  Cenozoic  formations 102 

of  American  Mosozoic  formatioas 11 

Strongylocent^otida^ 216, 223 

Strongylocentrotus  drobacliiensis 216, 223, 3SS 

franciscanus 223 

purpuratus 223 

Synapta  sp 177 

Synaptid;e :....' 177 

T. 

Texas,  stratigraphic  distribution  of  echinfiderms  in 14 

Toxaster  elegans 88, 89 

texanus 86 

ungula 83 

Toxopneustes  variegatus 222 

Trematopygus  crucifer 71 

cruciferus 71-72,  SS7, 253 

Tretocidaris  perplexa 115 

Triassic  echinoderms,  descriptions  of 21-24 

scarcity  of 9 

types  represented  among 12-13 

Triplechinidae 63-65, 118, 159, 181-182, 222 

Tuomey,  M.,  species  named  after 126 

U. 

Uintacrinida? 36-38 

Uintacrinus  socialis 36-38,«35 

V. 

Vaughan,  T.  Wayland,  species  named  after 160 

Verrm,  A.  E. ,  cited 222 

W. 

Weaver ,  C .  E , ,  cited 209, 215, 221 

Weller,  Stuart,  cited 40 

Whitfield,  R.  P.,  cited 29 

Z. 

Zenometra  conoideus 112 

Zy^gophiurse 23, 29, 43-44, 178-179 


o 


